| Title: | Sensitivity Analysis Tools for Regression Models |
|---|---|
| Description: | Implements a suite of sensitivity analysis tools that extends the traditional omitted variable bias framework and makes it easier to understand the impact of omitted variables in regression models, as discussed in Cinelli, C. and Hazlett, C. (2020), "Making Sense of Sensitivity: Extending Omitted Variable Bias." Journal of the Royal Statistical Society, Series B (Statistical Methodology) <doi:10.1111/rssb.12348>. |
| Authors: | Carlos Cinelli [aut, cre], Jeremy Ferwerda [aut], Chad Hazlett [aut], Danielle Tsao [ctb], Aaron Rudkin [ctb], Grigorij Ljubownikow [ctb] |
| Maintainer: | Carlos Cinelli <[email protected]> |
| License: | GPL-3 |
| Version: | 0.1.6 |
| Built: | 2024-08-22 06:49:46 UTC |
| Source: | CRAN |
The sensemakr package implements a suite of sensitivity analysis tools that makes it easier to understand the impact of omitted variables in linear regression models, as discussed in Cinelli and Hazlett (2020).
The main function of the package is sensemakr, which computes the most common sensitivity analysis results.
After running sensemakr you may directly use the plot and print methods in the returned object.
You may also use the other sensitivity functions of the package directly, such as the functions for sensitivity plots
(ovb_contour_plot, ovb_extreme_plot) the functions for computing bias-adjusted estimates and t-values (adjusted_estimate, adjusted_t),
the functions for computing the robustness value and partial R2 (robustness_value, partial_r2), or the functions for bounding the strength
of unobserved confounders (ovb_bounds), among others.
More information can be found on the help documentation, vignettes and related papers.
Cinelli, C. and Hazlett, C. (2020), "Making Sense of Sensitivity: Extending Omitted Variable Bias." Journal of the Royal Statistical Society, Series B (Statistical Methodology).
# loads dataset data("darfur") # runs regression model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # runs sensemakr for sensitivity analysis sensitivity <- sensemakr(model, treatment = "directlyharmed", benchmark_covariates = "female", kd = 1:3) # short description of results sensitivity # long description of results summary(sensitivity) # plot bias contour of point estimate plot(sensitivity) # plot bias contour of t-value plot(sensitivity, sensitivity.of = "t-value") # plot extreme scenario plot(sensitivity, type = "extreme") # latex code for sensitivity table ovb_minimal_reporting(sensitivity) # data.frame with sensitivity statistics sensitivity$sensitivity_stats # data.frame with bounds on the strengh of confounders sensitivity$bounds ### Using sensitivity functions directly ### # robustness value of directly harmed q = 1 (reduce estimate to zero) robustness_value(model, covariates = "directlyharmed") # robustness value of directly harmed q = 1/2 (reduce estimate in half) robustness_value(model, covariates = "directlyharmed", q = 1/2) # robustness value of directly harmed q = 1/2, alpha = 0.05 robustness_value(model, covariates = "directlyharmed", q = 1/2, alpha = 0.05) # partial R2 of directly harmed with peacefactor partial_r2(model, covariates = "directlyharmed") # partial R2 of female with peacefactor partial_r2(model, covariates = "female") # data.frame with sensitivity statistics sensitivity_stats(model, treatment = "directlyharmed") # bounds on the strength of confounders using female and age ovb_bounds(model, treatment = "directlyharmed", benchmark_covariates = c("female", "age"), kd = 1:3) # adjusted estimate given hypothetical strength of confounder adjusted_estimate(model, treatment = "directlyharmed", r2dz.x = 0.1, r2yz.dx = 0.1) # adjusted t-value given hypothetical strength of confounder adjusted_t(model, treatment = "directlyharmed", r2dz.x = 0.1, r2yz.dx = 0.1) # bias contour plot directly from lm model ovb_contour_plot(model, treatment = "directlyharmed", benchmark_covariates = "female", kd = 1:3) # extreme scenario plot directly from lm model ovb_extreme_plot(model, treatment = "directlyharmed", benchmark_covariates = "female", kd = 1:3, lim = 0.05)# loads dataset data("darfur") # runs regression model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # runs sensemakr for sensitivity analysis sensitivity <- sensemakr(model, treatment = "directlyharmed", benchmark_covariates = "female", kd = 1:3) # short description of results sensitivity # long description of results summary(sensitivity) # plot bias contour of point estimate plot(sensitivity) # plot bias contour of t-value plot(sensitivity, sensitivity.of = "t-value") # plot extreme scenario plot(sensitivity, type = "extreme") # latex code for sensitivity table ovb_minimal_reporting(sensitivity) # data.frame with sensitivity statistics sensitivity$sensitivity_stats # data.frame with bounds on the strengh of confounders sensitivity$bounds ### Using sensitivity functions directly ### # robustness value of directly harmed q = 1 (reduce estimate to zero) robustness_value(model, covariates = "directlyharmed") # robustness value of directly harmed q = 1/2 (reduce estimate in half) robustness_value(model, covariates = "directlyharmed", q = 1/2) # robustness value of directly harmed q = 1/2, alpha = 0.05 robustness_value(model, covariates = "directlyharmed", q = 1/2, alpha = 0.05) # partial R2 of directly harmed with peacefactor partial_r2(model, covariates = "directlyharmed") # partial R2 of female with peacefactor partial_r2(model, covariates = "female") # data.frame with sensitivity statistics sensitivity_stats(model, treatment = "directlyharmed") # bounds on the strength of confounders using female and age ovb_bounds(model, treatment = "directlyharmed", benchmark_covariates = c("female", "age"), kd = 1:3) # adjusted estimate given hypothetical strength of confounder adjusted_estimate(model, treatment = "directlyharmed", r2dz.x = 0.1, r2yz.dx = 0.1) # adjusted t-value given hypothetical strength of confounder adjusted_t(model, treatment = "directlyharmed", r2dz.x = 0.1, r2yz.dx = 0.1) # bias contour plot directly from lm model ovb_contour_plot(model, treatment = "directlyharmed", benchmark_covariates = "female", kd = 1:3) # extreme scenario plot directly from lm model ovb_extreme_plot(model, treatment = "directlyharmed", benchmark_covariates = "female", kd = 1:3, lim = 0.05)
Convenience function to add bounds on a sensitivity contour plot created with ovb_contour_plot.
add_bound_to_contour(...) ## S3 method for class 'lm' add_bound_to_contour( model, benchmark_covariates, kd = 1, ky = kd, bound_label = NULL, treatment = plot.env$treatment, reduce = plot.env$reduce, sensitivity.of = plot.env$sensitivity.of, label.text = TRUE, cex.label.text = 0.7, label.bump.x = plot.env$lim.x * (1/15), label.bump.y = plot.env$lim.y * (1/15), round = 2, ... ) ## S3 method for class 'fixest' add_bound_to_contour( model, benchmark_covariates, kd = 1, ky = kd, bound_label = NULL, treatment = plot.env$treatment, reduce = plot.env$reduce, sensitivity.of = plot.env$sensitivity.of, label.text = TRUE, cex.label.text = 0.7, label.bump.x = plot.env$lim.x * (1/15), label.bump.y = plot.env$lim.y * (1/15), round = 2, ... ) ## S3 method for class 'numeric' add_bound_to_contour( r2dz.x, r2yz.dx, bound_value = NULL, bound_label = NULL, label.text = TRUE, cex.label.text = 0.7, font.label.text = 1, label.bump.x = plot.env$lim.x * (1/15), label.bump.y = plot.env$lim.y * (1/15), round = 2, point.pch = 23, point.col = "black", point.bg = "red", point.cex = 1, point.font = 1, ... )add_bound_to_contour(...) ## S3 method for class 'lm' add_bound_to_contour( model, benchmark_covariates, kd = 1, ky = kd, bound_label = NULL, treatment = plot.env$treatment, reduce = plot.env$reduce, sensitivity.of = plot.env$sensitivity.of, label.text = TRUE, cex.label.text = 0.7, label.bump.x = plot.env$lim.x * (1/15), label.bump.y = plot.env$lim.y * (1/15), round = 2, ... ) ## S3 method for class 'fixest' add_bound_to_contour( model, benchmark_covariates, kd = 1, ky = kd, bound_label = NULL, treatment = plot.env$treatment, reduce = plot.env$reduce, sensitivity.of = plot.env$sensitivity.of, label.text = TRUE, cex.label.text = 0.7, label.bump.x = plot.env$lim.x * (1/15), label.bump.y = plot.env$lim.y * (1/15), round = 2, ... ) ## S3 method for class 'numeric' add_bound_to_contour( r2dz.x, r2yz.dx, bound_value = NULL, bound_label = NULL, label.text = TRUE, cex.label.text = 0.7, font.label.text = 1, label.bump.x = plot.env$lim.x * (1/15), label.bump.y = plot.env$lim.y * (1/15), round = 2, point.pch = 23, point.col = "black", point.bg = "red", point.cex = 1, point.font = 1, ... )
... |
arguments passed to other methods. |
model |
An |
benchmark_covariates |
The user has two options: (i) character vector of the names of covariates that will be used to bound the plausible strength of the unobserved confounders. Each variable will be considered separately; (ii) a named list with character vector names of covariates that will be used, as a group, to bound the plausible strength of the unobserved confounders. The names of the list will be used for the benchmark labels. Note: for factor variables with more than two levels, you need to provide the name of each level as encoded in the |
kd |
numeric vector. Parameterizes how many times stronger the confounder is related to the treatment in comparison to the observed benchmark covariate.
Default value is |
ky |
numeric vector. Parameterizes how many times stronger the confounder is related to the outcome in comparison to the observed benchmark covariate.
Default value is the same as |
bound_label |
label to bounds provided manually in |
treatment |
A character vector with the name of the treatment variable of the model. |
reduce |
should the bias adjustment reduce or increase the
absolute value of the estimated coefficient? Default is |
sensitivity.of |
should the contour plot show adjusted estimates ( |
label.text |
should label texts be plotted? Default is |
cex.label.text |
size of the label text. |
label.bump.x |
bump on the x coordinate of label text. |
label.bump.y |
bump on the y coordinate of label text. |
round |
integer indicating the number of decimal places to be used for rounding. |
r2dz.x |
hypothetical partial R2 of unobserved confounder Z with treatment D, given covariates X. |
r2yz.dx |
hypothetical partial R2 of unobserved confounder Z with outcome Y, given covariates X and treatment D. |
bound_value |
value to be printed in label bound. |
font.label.text |
font for the label text. |
point.pch |
plotting character for |
point.col |
color code or name for |
point.bg |
background (fill) color for |
point.cex |
size of |
point.font |
font for |
The function adds bounds in an existing contour plot and returns 'NULL'.
# runs regression model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # contour plot ovb_contour_plot(model = model, treatment = "directlyharmed") # add bound 3/1 times stronger than female add_bound_to_contour(model = model, benchmark_covariates = "female", kd = 3, ky = 1) # add bound 50/2 times stronger than age add_bound_to_contour(model = model, benchmark_covariates = "age", kd = 50, ky = 2)# runs regression model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # contour plot ovb_contour_plot(model = model, treatment = "directlyharmed") # add bound 3/1 times stronger than female add_bound_to_contour(model = model, benchmark_covariates = "female", kd = 3, ky = 1) # add bound 50/2 times stronger than age add_bound_to_contour(model = model, benchmark_covariates = "age", kd = 50, ky = 2)
These functions compute bias adjusted critical values for a given postulated strength of omitted variable with the dependent and independent variables of an OLS regression.
Researchers can thus easily perform sensitivity analysis by simply substituting traditional thresholds with bias-adjusted thresholds, when testing a particular null hypothesis, or when constructing confidence intervals.
adjusted_critical_value(r2dz.x, r2yz.dx, dof, alpha = 0.05, max = T)adjusted_critical_value(r2dz.x, r2yz.dx, dof, alpha = 0.05, max = T)
r2dz.x |
hypothetical partial R2 of unobserved confounder Z with treatment D, given covariates X. |
r2yz.dx |
hypothetical partial R2 of unobserved confounder Z with outcome Y, given covariates X and treatment D. |
dof |
residual degrees of freedom of the regression. |
alpha |
significance level. Default is '0.05'. |
max |
if 'TRUE' (default) it computes the worst possible adjusted critical threshold for an omitted variable with strength limited by 'r2dz.x' and 'r2yz.dx'. |
Numeric vector with bias-adjusted critical values.
Cinelli, C. and Hazlett, C. (2020), "Making Sense of Sensitivity: Extending Omitted Variable Bias." Journal of the Royal Statistical Society, Series B (Statistical Methodology).
Cinelli, C. and Hazlett, C. (2023), "An Omitted Variable Bias Framework for Sensitivity Analysis of Instrumental Variables."
# traditional critical threshold (no confounding) is 1.96 (dof = 1e4) adjusted_critical_value(r2dz.x = 0, r2yz.dx = 0, dof = 1e4, alpha = 0.05) # adjusted critical threshold, r2 = 1% is 2.96 (dof = 1e4) adjusted_critical_value(r2dz.x = 0.01, r2yz.dx = 0.01, dof = 1e4, alpha = 0.05)# traditional critical threshold (no confounding) is 1.96 (dof = 1e4) adjusted_critical_value(r2dz.x = 0, r2yz.dx = 0, dof = 1e4, alpha = 0.05) # adjusted critical threshold, r2 = 1% is 2.96 (dof = 1e4) adjusted_critical_value(r2dz.x = 0.01, r2yz.dx = 0.01, dof = 1e4, alpha = 0.05)
These functions compute bias adjusted estimates (adjusted_estimate),
standard-errors (adjusted_se) and t-values (adjusted_t),
given a hypothetical strength of the confounder in the partial R2 parameterization.
The functions work either with an lm object, or directly
passing in numerical inputs, such as the
current coefficient estimate, standard error and degrees of freedom.
adjusted_estimate(...) ## S3 method for class 'lm' adjusted_estimate(model, treatment, r2dz.x, r2yz.dx, reduce = TRUE, ...) ## S3 method for class 'fixest' adjusted_estimate(model, treatment, r2dz.x, r2yz.dx, reduce = TRUE, ...) ## S3 method for class 'numeric' adjusted_estimate(estimate, se, dof, r2dz.x, r2yz.dx, reduce = TRUE, ...) adjusted_se(...) ## S3 method for class 'numeric' adjusted_se(se, dof, r2dz.x, r2yz.dx, ...) ## S3 method for class 'lm' adjusted_se(model, treatment, r2dz.x, r2yz.dx, ...) ## S3 method for class 'fixest' adjusted_se(model, treatment, r2dz.x, r2yz.dx, message = TRUE, ...) adjusted_ci(...) ## S3 method for class 'lm' adjusted_ci( model, treatment, r2dz.x, r2yz.dx, which = c("both", "lwr", "upr"), reduce = TRUE, alpha = 0.05, ... ) ## S3 method for class 'fixest' adjusted_ci( model, treatment, r2dz.x, r2yz.dx, which = c("both", "lwr", "upr"), reduce = TRUE, alpha = 0.05, message = T, ... ) ## S3 method for class 'numeric' adjusted_ci( estimate, se, dof, r2dz.x, r2yz.dx, which = c("both", "lwr", "upr"), reduce = TRUE, alpha = 0.05, ... ) adjusted_t(...) ## S3 method for class 'lm' adjusted_t(model, treatment, r2dz.x, r2yz.dx, reduce = TRUE, h0 = 0, ...) ## S3 method for class 'fixest' adjusted_t( model, treatment, r2dz.x, r2yz.dx, reduce = TRUE, h0 = 0, message = T, ... ) ## S3 method for class 'numeric' adjusted_t(estimate, se, dof, r2dz.x, r2yz.dx, reduce = TRUE, h0 = 0, ...) adjusted_partial_r2(...) ## S3 method for class 'numeric' adjusted_partial_r2( estimate, se, dof, r2dz.x, r2yz.dx, reduce = TRUE, h0 = 0, ... ) ## S3 method for class 'lm' adjusted_partial_r2( model, treatment, r2dz.x, r2yz.dx, reduce = TRUE, h0 = 0, ... ) ## S3 method for class 'fixest' adjusted_partial_r2( model, treatment, r2dz.x, r2yz.dx, reduce = TRUE, h0 = 0, ... ) bias(...) ## S3 method for class 'numeric' bias(se, dof, r2dz.x, r2yz.dx, ...) ## S3 method for class 'lm' bias(model, treatment, r2dz.x, r2yz.dx, ...) ## S3 method for class 'fixest' bias(model, treatment, r2dz.x, r2yz.dx, ...) relative_bias(...) ## S3 method for class 'lm' relative_bias(model, treatment, r2dz.x, r2yz.dx, ...) ## S3 method for class 'fixest' relative_bias(model, treatment, r2dz.x, r2yz.dx, ...) ## S3 method for class 'numeric' relative_bias(estimate, se, dof, r2dz.x, r2yz.dx, ...) rel_bias(r.est, est)adjusted_estimate(...) ## S3 method for class 'lm' adjusted_estimate(model, treatment, r2dz.x, r2yz.dx, reduce = TRUE, ...) ## S3 method for class 'fixest' adjusted_estimate(model, treatment, r2dz.x, r2yz.dx, reduce = TRUE, ...) ## S3 method for class 'numeric' adjusted_estimate(estimate, se, dof, r2dz.x, r2yz.dx, reduce = TRUE, ...) adjusted_se(...) ## S3 method for class 'numeric' adjusted_se(se, dof, r2dz.x, r2yz.dx, ...) ## S3 method for class 'lm' adjusted_se(model, treatment, r2dz.x, r2yz.dx, ...) ## S3 method for class 'fixest' adjusted_se(model, treatment, r2dz.x, r2yz.dx, message = TRUE, ...) adjusted_ci(...) ## S3 method for class 'lm' adjusted_ci( model, treatment, r2dz.x, r2yz.dx, which = c("both", "lwr", "upr"), reduce = TRUE, alpha = 0.05, ... ) ## S3 method for class 'fixest' adjusted_ci( model, treatment, r2dz.x, r2yz.dx, which = c("both", "lwr", "upr"), reduce = TRUE, alpha = 0.05, message = T, ... ) ## S3 method for class 'numeric' adjusted_ci( estimate, se, dof, r2dz.x, r2yz.dx, which = c("both", "lwr", "upr"), reduce = TRUE, alpha = 0.05, ... ) adjusted_t(...) ## S3 method for class 'lm' adjusted_t(model, treatment, r2dz.x, r2yz.dx, reduce = TRUE, h0 = 0, ...) ## S3 method for class 'fixest' adjusted_t( model, treatment, r2dz.x, r2yz.dx, reduce = TRUE, h0 = 0, message = T, ... ) ## S3 method for class 'numeric' adjusted_t(estimate, se, dof, r2dz.x, r2yz.dx, reduce = TRUE, h0 = 0, ...) adjusted_partial_r2(...) ## S3 method for class 'numeric' adjusted_partial_r2( estimate, se, dof, r2dz.x, r2yz.dx, reduce = TRUE, h0 = 0, ... ) ## S3 method for class 'lm' adjusted_partial_r2( model, treatment, r2dz.x, r2yz.dx, reduce = TRUE, h0 = 0, ... ) ## S3 method for class 'fixest' adjusted_partial_r2( model, treatment, r2dz.x, r2yz.dx, reduce = TRUE, h0 = 0, ... ) bias(...) ## S3 method for class 'numeric' bias(se, dof, r2dz.x, r2yz.dx, ...) ## S3 method for class 'lm' bias(model, treatment, r2dz.x, r2yz.dx, ...) ## S3 method for class 'fixest' bias(model, treatment, r2dz.x, r2yz.dx, ...) relative_bias(...) ## S3 method for class 'lm' relative_bias(model, treatment, r2dz.x, r2yz.dx, ...) ## S3 method for class 'fixest' relative_bias(model, treatment, r2dz.x, r2yz.dx, ...) ## S3 method for class 'numeric' relative_bias(estimate, se, dof, r2dz.x, r2yz.dx, ...) rel_bias(r.est, est)
... |
arguments passed to other methods. |
model |
An |
treatment |
A character vector with the name of the treatment variable of the model. |
r2dz.x |
hypothetical partial R2 of unobserved confounder Z with treatment D, given covariates X. |
r2yz.dx |
hypothetical partial R2 of unobserved confounder Z with outcome Y, given covariates X and treatment D. |
reduce |
should the bias adjustment reduce or increase the
absolute value of the estimated coefficient? Default is |
estimate |
Coefficient estimate. |
se |
standard error of the coefficient estimate. |
dof |
residual degrees of freedom of the regression. |
message |
should messages be printed? Default = TRUE. |
which |
which limit of the confidence interval to show? Options are "both", lower limit ("lwr") or upper limit ("upr"). |
alpha |
significance level. |
h0 |
Null hypothesis for computation of the t-value. Default is zero. |
r.est |
restricted estimate. A numerical vector. |
est |
unrestricted estimate. A numerical vector. |
Numeric vector with bias, adjusted estimate, standard error, or t-value.
Cinelli, C. and Hazlett, C. (2020), "Making Sense of Sensitivity: Extending Omitted Variable Bias." Journal of the Royal Statistical Society, Series B (Statistical Methodology).
# loads data data("darfur") # fits model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # computes adjusted estimate for confounder with r2dz.x = 0.05, r2yz.dx = 0.05 adjusted_estimate(model, treatment = "directlyharmed", r2dz.x = 0.05, r2yz.dx = 0.05) # computes adjusted SE for confounder with r2dz.x = 0.05, r2yz.dx = 0.05 adjusted_se(model, treatment = "directlyharmed", r2dz.x = 0.05, r2yz.dx = 0.05) # computes adjusted t-value for confounder with r2dz.x = 0.05, r2yz.dx = 0.05 adjusted_t(model, treatment = "directlyharmed", r2dz.x = 0.05, r2yz.dx = 0.05) # Alternatively, pass in numerical values directly. adjusted_estimate(estimate = 0.09731582, se = 0.02325654, dof = 783, r2dz.x = 0.05, r2yz.dx = 0.05) adjusted_se(estimate = 0.09731582, se = 0.02325654, dof = 783, r2dz.x = 0.05, r2yz.dx = 0.05) adjusted_t(estimate = 0.09731582, se = 0.02325654, dof = 783, r2dz.x = 0.05, r2yz.dx = 0.05)# loads data data("darfur") # fits model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # computes adjusted estimate for confounder with r2dz.x = 0.05, r2yz.dx = 0.05 adjusted_estimate(model, treatment = "directlyharmed", r2dz.x = 0.05, r2yz.dx = 0.05) # computes adjusted SE for confounder with r2dz.x = 0.05, r2yz.dx = 0.05 adjusted_se(model, treatment = "directlyharmed", r2dz.x = 0.05, r2yz.dx = 0.05) # computes adjusted t-value for confounder with r2dz.x = 0.05, r2yz.dx = 0.05 adjusted_t(model, treatment = "directlyharmed", r2dz.x = 0.05, r2yz.dx = 0.05) # Alternatively, pass in numerical values directly. adjusted_estimate(estimate = 0.09731582, se = 0.02325654, dof = 783, r2dz.x = 0.05, r2yz.dx = 0.05) adjusted_se(estimate = 0.09731582, se = 0.02325654, dof = 783, r2dz.x = 0.05, r2yz.dx = 0.05) adjusted_t(estimate = 0.09731582, se = 0.02325654, dof = 783, r2dz.x = 0.05, r2yz.dx = 0.05)
Data on support for the 2016 referendum for peace with the FARC in Colombia, as discussed in Hazlett and Parente (2020).
The main "treatment"
variables are santos2014, which indicates the share of town population voting in support of
Santos in the 2014 Presidential election, and fat_2011to2015_gtd, which indicates
the number of fatalities due to FARC violence between 2011 and 2015, again at the town level.
The main outcome of interest is yes_vote, the proportion (0-100) at the town-level
voting in support of the peace referendum. The question of interest in Hazlett and Parente (2020) is
what can be said about the causal effect of either violence (fatalities) or
of political affiliation with Santos, recognizing that analyses of either cannot
likely rule out all confounding.
colombiacolombia
A data frame with 1123 rows and 16 columns.
Name for the provincial level unit, called departments or departamentos, of which there are 32 in the country.
Short code for the department
Name for the town, which is the smallest electoral unit available and is the unit of analysis.
Code for the town.
Total eligible voters in the town
Proportion (out of 100) voting in favor of the peace deal.
Proportion (out of 100) voting for Santos in 2010 presidential election.
Proportion (out of 100) voting for Santos in the 2014 presidential election.
The town-level GDP per capita.
Town-level population in 2013.
Town's mean elevation.
Sum of all known fatalities due to FARC violence in the town (from Global Terrorism Database, GTD).
Sum of fatalities due to FARC in the town in 2001 to 2005 (from GTD).
Sum of fatalities due to FARC in the town in 2006 to 2010 (from GTD).
Sum of fatalities due to FARC in the town in 2011 to 2015 (from GTD).
Sum of fatalities due to FARC in the town in 2010 to 2013 (from GTD).
Hazlett, C., and Parente, F. (2020). "Who supports peace with the FARC? A sensitivity-based approach under imperfect identification"
# loads data data(colombia) #----------------------------------------------------- # Violence Models #----------------------------------------------------- ### Model 1 (bivariate) model1 <- lm(yes_vote ~ fat_2001to2005_gtd, data = colombia) ### Model 2 (more controls, and lagged violence.) model2 <- lm(yes_vote ~ fat_2001to2005_gtd + fat_2006to2010_gtd + fat_2011to2015_gtd + total_eligible + santos10 + gdppc , data = colombia) ### Sensitivity analysis - Model 2, for effect of most recent violence. sense.model2 <- sensemakr(model2, treatment = "fat_2011to2015_gtd", benchmark = "santos10", kd = 1) ### contour plot point estimate plot(sense.model2) ### contour plot t-value plot(sense.model2, sensitivity.of = "t-value") #--------------------------------------------- # Political Affiliation Model #--------------------------------------------- ### Model 3: santos2014 as measure of political support for Santos, with control variables. model3 <- lm(yes_vote ~ santos14 + fat_2010to2013 + elev + gdppc + pop13, data = colombia) ### Sensitivity analysis - Model 3 sense.model3 <- sensemakr(model3, treatment = "santos14", benchmark = c("gdppc","elev"), kd = 3) summary(sense.model3) ### contour plot point estimate plot(sense.model3, lim = .9) ### contour plot t-value plot(sense.model3, sensitivity.of = "t-value", lim = 0.9)# loads data data(colombia) #----------------------------------------------------- # Violence Models #----------------------------------------------------- ### Model 1 (bivariate) model1 <- lm(yes_vote ~ fat_2001to2005_gtd, data = colombia) ### Model 2 (more controls, and lagged violence.) model2 <- lm(yes_vote ~ fat_2001to2005_gtd + fat_2006to2010_gtd + fat_2011to2015_gtd + total_eligible + santos10 + gdppc , data = colombia) ### Sensitivity analysis - Model 2, for effect of most recent violence. sense.model2 <- sensemakr(model2, treatment = "fat_2011to2015_gtd", benchmark = "santos10", kd = 1) ### contour plot point estimate plot(sense.model2) ### contour plot t-value plot(sense.model2, sensitivity.of = "t-value") #--------------------------------------------- # Political Affiliation Model #--------------------------------------------- ### Model 3: santos2014 as measure of political support for Santos, with control variables. model3 <- lm(yes_vote ~ santos14 + fat_2010to2013 + elev + gdppc + pop13, data = colombia) ### Sensitivity analysis - Model 3 sense.model3 <- sensemakr(model3, treatment = "santos14", benchmark = c("gdppc","elev"), kd = 3) summary(sense.model3) ### contour plot point estimate plot(sense.model3, lim = .9) ### contour plot t-value plot(sense.model3, sensitivity.of = "t-value", lim = 0.9)
Data on attitudes of Darfurian refugees in eastern Chad. The main "treatment"
variable is directlyharmed, which indicates that the individual was physically
injured during attacks on villages in Darfur, largely between 2003 and 2004.
The main outcome of interest is peacefactor, a measure of pro-peace
attitudes.
Key covariates include herder_dar
(whether they were a herder in Darfur), farmer_dar (whether they were a
farmer in Darfur), age, female (indicator for female), and
past_voted (whether they report having voted in an earlier election,
prior to the conflict).
darfurdarfur
A data frame with 1276 rows and 14 columns.
If elections were held in Darfur in the future, would you vote? (0/1)
A measure of pro-peace attitudes, from a factor analysis of several questions. Rescaled such that 0 is minimally pro-peace and 1 is maximally pro-peace.
Would you be willing to make peace with your former enemies? (0/1)
Would you be willing to make peace with Janjweed individuals who carried out violence? (0/1)
Would you be willing to make peace with the tribes that were part of the Janjaweed? (0/1)
Should Government of Sudan soldiers who perpetrated attacks on civilians be executed? (0/1)
A binary variable indicating whether the respondent was personally physically injured during attacks on villages in Darfur largely between 2003-2004. 529 respondents report being personally injured, while 747 do not report being injured.
Age of respondent in whole integer years. Ages in the data range from 18 to 100.
The respondent was a farmer in Darfur (0/1). 1,051 respondents were farmers, 225 were not.
The respondent was a herder in Darfur (0/1). 190 respondents were farmers, 1,086 were not.
The respondent reported having voted in a previous election before the conflict (0/1). 821 respondents reported having voted in a previous election, 455 reported not having voted in a previous election.
Household size while in Darfur.
Factor variable indicating village of respondent. 486 unique villages are accounted for in the data.
The respondent identifies as female (0/1). 582 respondents are female-identified, 694 are not.
Cinelli, C. and Hazlett, C. (2020), "Making Sense of Sensitivity: Extending Omitted Variable Bias." Journal of the Royal Statistical Society, Series B (Statistical Methodology).
Hazlett, Chad. (2019) "Angry or Weary? How Violence Impacts Attitudes toward Peace among Darfurian Refugees." Journal of Conflict Resolution: 0022002719879217.
This function computes the partial R2 of a group of covariates in a linear regression model.
group_partial_r2(...) ## S3 method for class 'lm' group_partial_r2(model, covariates, ...) ## S3 method for class 'fixest' group_partial_r2(model, covariates, ...) ## S3 method for class 'numeric' group_partial_r2(F.stats, p, dof, ...)group_partial_r2(...) ## S3 method for class 'lm' group_partial_r2(model, covariates, ...) ## S3 method for class 'fixest' group_partial_r2(model, covariates, ...) ## S3 method for class 'numeric' group_partial_r2(F.stats, p, dof, ...)
... |
arguments passed to other methods. First argument should either be an |
model |
an |
covariates |
model covariates for which their grouped partial R2 will be computed. |
F.stats |
F-statistics for the group of covariates. |
p |
number of parameters in the model. |
dof |
residual degrees of freedom of the model. |
A numeric vector with the computed partial R2.
data("darfur") model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) group_partial_r2(model, covariates = c("female", "pastvoted"))data("darfur") model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) group_partial_r2(model, covariates = c("female", "pastvoted"))
Bounds on the strength of unobserved confounders using observed covariates, as in Cinelli and Hazlett (2020). The main generic function is ovb_bounds, which can compute both the bounds on the strength of confounding as well as the adjusted estimates, standard errors, t-values and confidence intervals.
Other functions that compute only the bounds on the strength of confounding are also provided. These functions may be useful when computing benchmarks for using only summary statistics from papers you see in print.
ovb_bounds(...) ## S3 method for class 'lm' ovb_bounds( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, reduce = TRUE, bound = c("partial r2", "partial r2 no D", "total r2"), adjusted_estimates = TRUE, alpha = 0.05, h0 = 0, ... ) ## S3 method for class 'fixest' ovb_bounds( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, reduce = TRUE, bound = c("partial r2", "partial r2 no D", "total r2"), adjusted_estimates = TRUE, alpha = 0.05, h0 = 0, message = T, ... ) ovb_partial_r2_bound(...) ## S3 method for class 'numeric' ovb_partial_r2_bound( r2dxj.x, r2yxj.dx, kd = 1, ky = kd, bound_label = "manual", ... ) ## S3 method for class 'lm' ovb_partial_r2_bound( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, adjusted_estimates = TRUE, alpha = 0.05, ... ) ## S3 method for class 'fixest' ovb_partial_r2_bound( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, adjusted_estimates = TRUE, alpha = 0.05, ... )ovb_bounds(...) ## S3 method for class 'lm' ovb_bounds( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, reduce = TRUE, bound = c("partial r2", "partial r2 no D", "total r2"), adjusted_estimates = TRUE, alpha = 0.05, h0 = 0, ... ) ## S3 method for class 'fixest' ovb_bounds( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, reduce = TRUE, bound = c("partial r2", "partial r2 no D", "total r2"), adjusted_estimates = TRUE, alpha = 0.05, h0 = 0, message = T, ... ) ovb_partial_r2_bound(...) ## S3 method for class 'numeric' ovb_partial_r2_bound( r2dxj.x, r2yxj.dx, kd = 1, ky = kd, bound_label = "manual", ... ) ## S3 method for class 'lm' ovb_partial_r2_bound( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, adjusted_estimates = TRUE, alpha = 0.05, ... ) ## S3 method for class 'fixest' ovb_partial_r2_bound( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, adjusted_estimates = TRUE, alpha = 0.05, ... )
... |
arguments passed to other methods. |
model |
An |
treatment |
A character vector with the name of the treatment variable of the model. |
benchmark_covariates |
The user has two options: (i) character vector of the names of covariates that will be used to bound the plausible strength of the unobserved confounders. Each variable will be considered separately; (ii) a named list with character vector names of covariates that will be used, as a group, to bound the plausible strength of the unobserved confounders. The names of the list will be used for the benchmark labels. Note: for factor variables with more than two levels, you need to provide the name of each level as encoded in the |
kd |
numeric vector. Parameterizes how many times stronger the confounder is related to the treatment in comparison to the observed benchmark covariate.
Default value is |
ky |
numeric vector. Parameterizes how many times stronger the confounder is related to the outcome in comparison to the observed benchmark covariate.
Default value is the same as |
reduce |
should the bias adjustment reduce or increase the
absolute value of the estimated coefficient? Default is |
bound |
type of bounding procedure. Currently only |
adjusted_estimates |
should the bounder also compute the adjusted estimates? Default is |
alpha |
significance level for computing the adjusted confidence intervals. Default is 0.05. |
h0 |
Null hypothesis for computation of the t-value. Default is zero. |
message |
should messages be printed? Default = TRUE. |
r2dxj.x |
partial R2 of covariate Xj with the treatment D (after partialling out the effect of the remaining covariates X, excluding Xj). |
r2yxj.dx |
partial R2 of covariate Xj with the outcome Y (after partialling out the effect of the remaining covariates X, excluding Xj). |
bound_label |
label to bounds provided manually in |
Currently it implements only the bounds based on partial R2. Other bounds will be implemented soon.
The function ovb_bounds returns a data.frame with the bounds on the strength of the unobserved confounder
as well with the adjusted point estimates, standard errors and t-values (optional, controlled by argument adjusted_estimates = TRUE).
The function 'ovb_partial_r2_bound()' returns only data.frame with the bounds on the strength of the unobserved confounder. Adjusted estimates, standard
errors and t-values (among other quantities) need to be computed manually by the user using those bounds with the functions adjusted_estimate, adjusted_se and adjusted_t.
Cinelli, C. and Hazlett, C. (2020), "Making Sense of Sensitivity: Extending Omitted Variable Bias." Journal of the Royal Statistical Society, Series B (Statistical Methodology).
Cinelli, C. and Hazlett, C. (2020), "Making Sense of Sensitivity: Extending Omitted Variable Bias." Journal of the Royal Statistical Society, Series B (Statistical Methodology).
Cinelli, C. and Hazlett, C. (2020), "Making Sense of Sensitivity: Extending Omitted Variable Bias." Journal of the Royal Statistical Society, Series B (Statistical Methodology).
# runs regression model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # bounds on the strength of confounders 1, 2, or 3 times as strong as female # and 1,2, or 3 times as strong as pastvoted ovb_bounds(model, treatment = "directlyharmed", benchmark_covariates = c("female", "pastvoted"), kd = 1:3) # run regression model model <- fixest::feols(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # bounds on the strength of confounders 1, 2, or 3 times as strong as female # and 1,2, or 3 times as strong as pastvoted ovb_bounds(model, treatment = "directlyharmed", benchmark_covariates = c("female", "pastvoted"), kd = 1:3) ######################################################### ## Let's construct bounds from summary statistics only ## ######################################################### # Suppose you didn't have access to the data, but only to # the treatment and outcome regression tables. # You can still compute the bounds. # Use the t statistic of female in the outcome regression # to compute the partial R2 of female with the outcome. r2yxj.dx <- partial_r2(t_statistic = -9.789, dof = 783) # Use the t-value of female in the *treatment* regression # to compute the partial R2 of female with the treatment r2dxj.x <- partial_r2(t_statistic = -2.680, dof = 783) # Compute manually bounds on the strength of confounders 1, 2, or 3 # times as strong as female bounds <- ovb_partial_r2_bound(r2dxj.x = r2dxj.x, r2yxj.dx = r2yxj.dx, kd = 1:3, ky = 1:3, bound_label = paste(1:3, "x", "female")) # Compute manually adjusted estimates bound.values <- adjusted_estimate(estimate = 0.0973, se = 0.0232, dof = 783, r2dz.x = bounds$r2dz.x, r2yz.dx = bounds$r2yz.dx) # Plot contours and bounds ovb_contour_plot(estimate = 0.0973, se = 0.0232, dof = 783) add_bound_to_contour(bounds, bound_value = bound.values)# runs regression model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # bounds on the strength of confounders 1, 2, or 3 times as strong as female # and 1,2, or 3 times as strong as pastvoted ovb_bounds(model, treatment = "directlyharmed", benchmark_covariates = c("female", "pastvoted"), kd = 1:3) # run regression model model <- fixest::feols(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # bounds on the strength of confounders 1, 2, or 3 times as strong as female # and 1,2, or 3 times as strong as pastvoted ovb_bounds(model, treatment = "directlyharmed", benchmark_covariates = c("female", "pastvoted"), kd = 1:3) ######################################################### ## Let's construct bounds from summary statistics only ## ######################################################### # Suppose you didn't have access to the data, but only to # the treatment and outcome regression tables. # You can still compute the bounds. # Use the t statistic of female in the outcome regression # to compute the partial R2 of female with the outcome. r2yxj.dx <- partial_r2(t_statistic = -9.789, dof = 783) # Use the t-value of female in the *treatment* regression # to compute the partial R2 of female with the treatment r2dxj.x <- partial_r2(t_statistic = -2.680, dof = 783) # Compute manually bounds on the strength of confounders 1, 2, or 3 # times as strong as female bounds <- ovb_partial_r2_bound(r2dxj.x = r2dxj.x, r2yxj.dx = r2yxj.dx, kd = 1:3, ky = 1:3, bound_label = paste(1:3, "x", "female")) # Compute manually adjusted estimates bound.values <- adjusted_estimate(estimate = 0.0973, se = 0.0232, dof = 783, r2dz.x = bounds$r2dz.x, r2yz.dx = bounds$r2yz.dx) # Plot contours and bounds ovb_contour_plot(estimate = 0.0973, se = 0.0232, dof = 783) add_bound_to_contour(bounds, bound_value = bound.values)
Contour plots of omitted variable bias for sensitivity analysis. The main inputs are an lm model, the treatment variable
and the covariates used for benchmarking the strength of unobserved confounding.
The horizontal axis of the plot shows hypothetical values of the partial R2 of the unobserved confounder(s) with the treatment.
The vertical axis shows hypothetical values of the partial R2 of the unobserved confounder(s) with the outcome.
The contour levels represent the adjusted estimates (or t-values) of the treatment effect.
The reference points are the bounds on the partial R2 of the unobserved confounder if it were k times “as strong” as the observed covariate used for benchmarking (see arguments kd and ky).
The dotted red line show the chosen critical threshold (for instance, zero): confounders with such strength (or stronger) are sufficient to invalidate the research conclusions.
All results are exact for single confounders and conservative for multiple/nonlinear confounders.
See Cinelli and Hazlett (2020) for details.
ovb_contour_plot(...) ## S3 method for class 'lm' ovb_contour_plot( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = "manual", sensitivity.of = c("estimate", "t-value", "lwr", "upr"), reduce = TRUE, estimate.threshold = 0, alpha = 0.05, t.threshold = NULL, nlevels = 10, col.contour = "grey40", col.thr.line = "red", label.text = TRUE, cex.label.text = 0.7, round = 3, ... ) ## S3 method for class 'fixest' ovb_contour_plot( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = "manual", sensitivity.of = c("estimate", "t-value", "lwr", "upr"), reduce = TRUE, estimate.threshold = 0, alpha = 0.05, t.threshold = NULL, nlevels = 10, col.contour = "grey40", col.thr.line = "red", label.text = TRUE, cex.label.text = 0.7, round = 3, ... ) ## S3 method for class 'formula' ovb_contour_plot( formula, method = c("lm", "feols"), vcov = "iid", data, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = NULL, sensitivity.of = c("estimate", "t-value", "lwr", "upr"), reduce = TRUE, estimate.threshold = 0, alpha = 0.05, t.threshold = NULL, nlevels = 10, col.contour = "grey40", col.thr.line = "red", label.text = TRUE, cex.label.text = 0.7, round = 3, ... ) ## S3 method for class 'numeric' ovb_contour_plot( estimate, se, dof, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = rep("manual", length(r2dz.x)), sensitivity.of = c("estimate", "t-value", "lwr", "upr"), reduce = TRUE, estimate.threshold = 0, alpha = 0.05, t.threshold = NULL, show.unadjusted = TRUE, lim = NULL, lim.x = lim, lim.y = lim, nlevels = 10, col.contour = "black", col.thr.line = "red", label.text = TRUE, cex.label.text = 0.7, label.bump.x = NULL, label.bump.y = NULL, xlab = NULL, ylab = NULL, cex.lab = 0.8, cex.axis = 0.8, cex.main = 1, asp = lim.x/lim.y, list.par = list(mar = c(4, 4, 1, 1), pty = "s"), round = 3, ... )ovb_contour_plot(...) ## S3 method for class 'lm' ovb_contour_plot( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = "manual", sensitivity.of = c("estimate", "t-value", "lwr", "upr"), reduce = TRUE, estimate.threshold = 0, alpha = 0.05, t.threshold = NULL, nlevels = 10, col.contour = "grey40", col.thr.line = "red", label.text = TRUE, cex.label.text = 0.7, round = 3, ... ) ## S3 method for class 'fixest' ovb_contour_plot( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = "manual", sensitivity.of = c("estimate", "t-value", "lwr", "upr"), reduce = TRUE, estimate.threshold = 0, alpha = 0.05, t.threshold = NULL, nlevels = 10, col.contour = "grey40", col.thr.line = "red", label.text = TRUE, cex.label.text = 0.7, round = 3, ... ) ## S3 method for class 'formula' ovb_contour_plot( formula, method = c("lm", "feols"), vcov = "iid", data, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = NULL, sensitivity.of = c("estimate", "t-value", "lwr", "upr"), reduce = TRUE, estimate.threshold = 0, alpha = 0.05, t.threshold = NULL, nlevels = 10, col.contour = "grey40", col.thr.line = "red", label.text = TRUE, cex.label.text = 0.7, round = 3, ... ) ## S3 method for class 'numeric' ovb_contour_plot( estimate, se, dof, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = rep("manual", length(r2dz.x)), sensitivity.of = c("estimate", "t-value", "lwr", "upr"), reduce = TRUE, estimate.threshold = 0, alpha = 0.05, t.threshold = NULL, show.unadjusted = TRUE, lim = NULL, lim.x = lim, lim.y = lim, nlevels = 10, col.contour = "black", col.thr.line = "red", label.text = TRUE, cex.label.text = 0.7, label.bump.x = NULL, label.bump.y = NULL, xlab = NULL, ylab = NULL, cex.lab = 0.8, cex.axis = 0.8, cex.main = 1, asp = lim.x/lim.y, list.par = list(mar = c(4, 4, 1, 1), pty = "s"), round = 3, ... )
... |
arguments passed to other methods. First argument should either be an |
model |
An |
treatment |
A character vector with the name of the treatment variable of the model. |
benchmark_covariates |
The user has two options: (i) character vector of the names of covariates that will be used to bound the plausible strength of the unobserved confounders. Each variable will be considered separately; (ii) a named list with character vector names of covariates that will be used, as a group, to bound the plausible strength of the unobserved confounders. The names of the list will be used for the benchmark labels. Note: for factor variables with more than two levels, you need to provide the name of each level as encoded in the |
kd |
numeric vector. Parameterizes how many times stronger the confounder is related to the treatment in comparison to the observed benchmark covariate.
Default value is |
ky |
numeric vector. Parameterizes how many times stronger the confounder is related to the outcome in comparison to the observed benchmark covariate.
Default value is the same as |
r2dz.x |
hypothetical partial R2 of unobserved confounder Z with treatment D, given covariates X. |
r2yz.dx |
hypothetical partial R2 of unobserved confounder Z with outcome Y, given covariates X and treatment D. |
bound_label |
label to bounds provided manually in |
sensitivity.of |
should the contour plot show adjusted estimates ( |
reduce |
should the bias adjustment reduce or increase the
absolute value of the estimated coefficient? Default is |
estimate.threshold |
critical threshold for the point estimate. |
alpha |
significance level |
t.threshold |
critical threshold for the t-value. |
nlevels |
number of levels for the contour plot. |
col.contour |
color of contour lines. |
col.thr.line |
color of threshold contour line. |
label.text |
should label texts be plotted? Default is |
cex.label.text |
size of the label text. |
round |
number of digits to show in contours and bound values |
formula |
an object of the class |
method |
the default is |
vcov |
the variance/covariance used in the estimation when using |
data |
data needed only when you pass a formula as first parameter. An object of the class |
estimate |
Coefficient estimate. |
se |
standard error of the coefficient estimate. |
dof |
residual degrees of freedom of the regression. |
show.unadjusted |
should the unadjusted estimates be shown? Default is 'TRUE'. |
lim |
sets limit for both axis. If 'NULL', limits are computed automatically. |
lim.x |
sets limit for x-axis. If 'NULL', limits are computed automatically. |
lim.y |
sets limit for y-axis. If 'NULL', limits are computed automatically. |
label.bump.x |
bump on the x coordinate of label text. |
label.bump.y |
bump on the y coordinate of label text. |
xlab |
label of x axis. If 'NULL', default label is used. |
ylab |
label of y axis. If 'NULL', default label is used. |
cex.lab |
The magnification to be used for x and y labels relative to the current setting of cex. |
cex.axis |
The magnification to be used for axis annotation relative to the current setting of cex. |
cex.main |
The magnification to be used for main titles relative to the current setting of cex. |
asp |
the y/x aspect ratio. Default is 1. |
list.par |
arguments to be passed to |
The function returns invisibly the data used for the contour plot (contour grid and bounds).
Cinelli, C. and Hazlett, C. (2020), "Making Sense of Sensitivity: Extending Omitted Variable Bias." Journal of the Royal Statistical Society, Series B (Statistical Methodology).
# runs regression model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # contour plot ovb_contour_plot(model, treatment = "directlyharmed", benchmark_covariates = "female", kd = 1:2)# runs regression model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # contour plot ovb_contour_plot(model, treatment = "directlyharmed", benchmark_covariates = "female", kd = 1:2)
Extreme scenario plots of omitted variable bias for sensitivity analysis. The main inputs are an lm model, the treatment variable
and the covariates used for benchmarking the strength of unobserved confounding.
The horizontal axis shows the partial R2 of the unobserved confounder(s) with the treatment. The vertical axis shows the adjusted treatment effect estimate.
The partial R2 of the confounder with the outcome is represented by different curves for each scenario, as given by the parameter r2yz.dx.
The red marks on horizontal axis are bounds on the partial R2 of the unobserved confounder kd times as strong as the covariates used for benchmarking.
The dotted red line represent the threshold for the effect estimate deemed to be problematic (for instance, zero).
See Cinelli and Hazlett (2020) for details.
ovb_extreme_plot(...) ## S3 method for class 'lm' ovb_extreme_plot( model, treatment, benchmark_covariates = NULL, kd = 1, r2yz.dx = c(1, 0.75, 0.5), r2dz.x = NULL, reduce = TRUE, threshold = 0, lim = min(c(r2dz.x + 0.1, 0.5)), legend = TRUE, cex.legend = 0.65, legend.bty = "n", ... ) ## S3 method for class 'fixest' ovb_extreme_plot( model, treatment, benchmark_covariates = NULL, kd = 1, r2yz.dx = c(1, 0.75, 0.5), r2dz.x = NULL, reduce = TRUE, threshold = 0, lim = min(c(r2dz.x + 0.1, 0.5)), legend = TRUE, cex.legend = 0.65, legend.bty = "n", ... ) ## S3 method for class 'formula' ovb_extreme_plot( formula, method = c("lm", "feols"), vcov = "iid", data, treatment, benchmark_covariates = NULL, kd = 1, r2yz.dx = c(1, 0.75, 0.5), r2dz.x = NULL, reduce = TRUE, threshold = 0, lim = min(c(r2dz.x + 0.1, 0.5)), legend = TRUE, cex.legend = 0.65, legend.bty = "n", ... ) ## S3 method for class 'numeric' ovb_extreme_plot( estimate, se, dof, r2dz.x = NULL, r2yz.dx = c(1, 0.75, 0.5), reduce = TRUE, threshold = 0, lim = min(c(r2dz.x + 0.1, 0.5)), legend = TRUE, legend.title = NULL, cex.legend = 0.65, legend.bty = "n", xlab = NULL, ylab = NULL, cex.lab = 0.7, cex.axis = 0.7, list.par = list(oma = c(1, 1, 1, 1)), ... )ovb_extreme_plot(...) ## S3 method for class 'lm' ovb_extreme_plot( model, treatment, benchmark_covariates = NULL, kd = 1, r2yz.dx = c(1, 0.75, 0.5), r2dz.x = NULL, reduce = TRUE, threshold = 0, lim = min(c(r2dz.x + 0.1, 0.5)), legend = TRUE, cex.legend = 0.65, legend.bty = "n", ... ) ## S3 method for class 'fixest' ovb_extreme_plot( model, treatment, benchmark_covariates = NULL, kd = 1, r2yz.dx = c(1, 0.75, 0.5), r2dz.x = NULL, reduce = TRUE, threshold = 0, lim = min(c(r2dz.x + 0.1, 0.5)), legend = TRUE, cex.legend = 0.65, legend.bty = "n", ... ) ## S3 method for class 'formula' ovb_extreme_plot( formula, method = c("lm", "feols"), vcov = "iid", data, treatment, benchmark_covariates = NULL, kd = 1, r2yz.dx = c(1, 0.75, 0.5), r2dz.x = NULL, reduce = TRUE, threshold = 0, lim = min(c(r2dz.x + 0.1, 0.5)), legend = TRUE, cex.legend = 0.65, legend.bty = "n", ... ) ## S3 method for class 'numeric' ovb_extreme_plot( estimate, se, dof, r2dz.x = NULL, r2yz.dx = c(1, 0.75, 0.5), reduce = TRUE, threshold = 0, lim = min(c(r2dz.x + 0.1, 0.5)), legend = TRUE, legend.title = NULL, cex.legend = 0.65, legend.bty = "n", xlab = NULL, ylab = NULL, cex.lab = 0.7, cex.axis = 0.7, list.par = list(oma = c(1, 1, 1, 1)), ... )
... |
arguments passed to other methods. First argument should either be an |
model |
An |
treatment |
A character vector with the name of the treatment variable of the model. |
benchmark_covariates |
The user has two options: (i) character vector of the names of covariates that will be used to bound the plausible strength of the unobserved confounders. Each variable will be considered separately; (ii) a named list with character vector names of covariates that will be used, as a group, to bound the plausible strength of the unobserved confounders. The names of the list will be used for the benchmark labels. Note: for factor variables with more than two levels, you need to provide the name of each level as encoded in the |
kd |
numeric vector. Parameterizes how many times stronger the confounder is related to the treatment in comparison to the observed benchmark covariate.
Default value is |
r2yz.dx |
hypothetical partial R2 of unobserved confounder Z with outcome Y, given covariates X and treatment D. |
r2dz.x |
hypothetical partial R2 of unobserved confounder Z with treatment D, given covariates X. |
reduce |
should the bias adjustment reduce or increase the
absolute value of the estimated coefficient? Default is |
threshold |
estimate threshold. |
lim |
sets limit for both axis. If 'NULL', limits are computed automatically. |
legend |
should legend be plotted? Default is |
cex.legend |
size of the text for the legend. |
legend.bty |
legend box. See |
formula |
an object of the class |
method |
the default is |
vcov |
the variance/covariance used in the estimation when using |
data |
data needed only when you pass a formula as first parameter. An object of the class |
estimate |
Coefficient estimate. |
se |
standard error of the coefficient estimate. |
dof |
residual degrees of freedom of the regression. |
legend.title |
the legend title. If |
xlab |
label of x axis. If 'NULL', default label is used. |
ylab |
label of y axis. If 'NULL', default label is used. |
cex.lab |
The magnification to be used for x and y labels relative to the current setting of cex. |
cex.axis |
The magnification to be used for axis annotation relative to the current setting of cex. |
list.par |
arguments to be passed to |
The function returns invisibly the data used for the extreme plot.
Cinelli, C. and Hazlett, C. (2020), "Making Sense of Sensitivity: Extending Omitted Variable Bias." Journal of the Royal Statistical Society, Series B (Statistical Methodology).
# runs regression model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # extreme scenarios plot ovb_extreme_plot(model, treatment = "directlyharmed", benchmark_covariates = "female", kd = 1:2, lim = 0.05)# runs regression model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # extreme scenarios plot ovb_extreme_plot(model, treatment = "directlyharmed", benchmark_covariates = "female", kd = 1:2, lim = 0.05)
These functions computes the partial R2 and the partial (Cohen's) f2 for a linear regression model. The partial R2 describes how much of the residual variance of the outcome (after partialing out the other covariates) a covariate explains.
The partial R2 can be used as an extreme-scenario sensitivity analysis to omitted variables. Considering an unobserved confounder that explains 100% of the residual variance of the outcome, the partial R2 describes how strongly associated with the treatment this unobserved confounder would need to be in order to explain away the estimated effect. For details see Cinelli and Hazlett (2020).
The partial (Cohen's) f2 is a common measure of effect size (a transformation of the partial R2) that can also be used directly for sensitivity analysis using a bias factor table.
The function partial_r2 computes the partial R2. The function partial_f2 computes the partial f2 and the function partial_f the partial f.
They can take as input an lm object or you may pass directly t-value and degrees of freedom.
For partial R2 of groups of covariates, check group_partial_r2.
partial_r2(...) ## S3 method for class 'lm' partial_r2(model, covariates = NULL, ...) ## S3 method for class 'fixest' partial_r2(model, covariates = NULL, ...) ## S3 method for class 'numeric' partial_r2(t_statistic, dof, ...) partial_f2(...) ## S3 method for class 'numeric' partial_f2(t_statistic, dof, ...) ## S3 method for class 'lm' partial_f2(model, covariates = NULL, ...) ## S3 method for class 'fixest' partial_f2(model, covariates = NULL, ...) partial_f(...) ## S3 method for class 'fixest' partial_f(model, covariates = NULL, ...) ## S3 method for class 'lm' partial_f(model, covariates = NULL, ...) ## S3 method for class 'numeric' partial_f(t_statistic, dof, ...) ## S3 method for class 'numeric' partial_f(t_statistic, dof, ...) ## Default S3 method: partial_r2(model, ...)partial_r2(...) ## S3 method for class 'lm' partial_r2(model, covariates = NULL, ...) ## S3 method for class 'fixest' partial_r2(model, covariates = NULL, ...) ## S3 method for class 'numeric' partial_r2(t_statistic, dof, ...) partial_f2(...) ## S3 method for class 'numeric' partial_f2(t_statistic, dof, ...) ## S3 method for class 'lm' partial_f2(model, covariates = NULL, ...) ## S3 method for class 'fixest' partial_f2(model, covariates = NULL, ...) partial_f(...) ## S3 method for class 'fixest' partial_f(model, covariates = NULL, ...) ## S3 method for class 'lm' partial_f(model, covariates = NULL, ...) ## S3 method for class 'numeric' partial_f(t_statistic, dof, ...) ## S3 method for class 'numeric' partial_f(t_statistic, dof, ...) ## Default S3 method: partial_r2(model, ...)
... |
arguments passed to other methods. First argument should either be an |
model |
an |
covariates |
model covariates for which the partial R2 will be computed. Default is to compute the partial R2 of all covariates. |
t_statistic |
|
dof |
residual degrees of freedom of the regression |
A numeric vector with the computed partial R2, f2, or f.
Cinelli, C. and Hazlett, C. (2020), "Making Sense of Sensitivity: Extending Omitted Variable Bias." Journal of the Royal Statistical Society, Series B (Statistical Methodology).
# using an lm object ## loads data data("darfur") ## fits model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) ## partial R2 of the treatment (directly harmed) with the outcome (peacefactor) partial_r2(model, covariates = "directlyharmed") ## partial R2 of female with the outcome partial_r2(model, covariates = "female") # you can also provide the statistics directly partial_r2(t_statistic = 4.18445, dof = 783)# using an lm object ## loads data data("darfur") ## fits model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) ## partial R2 of the treatment (directly harmed) with the outcome (peacefactor) partial_r2(model, covariates = "directlyharmed") ## partial R2 of female with the outcome partial_r2(model, covariates = "female") # you can also provide the statistics directly partial_r2(t_statistic = 4.18445, dof = 783)
sensemakr
This function provides the contour and extreme scenario sensitivity plots of the sensitivity analysis results
obtained with the function sensemakr. They are basically dispatchers to the core plot functions ovb_contour_plot and
ovb_extreme_plot.
## S3 method for class 'sensemakr' plot(x, type = c("contour", "extreme"), ...)## S3 method for class 'sensemakr' plot(x, type = c("contour", "extreme"), ...)
x |
an object of class |
type |
type of sensitivity plot. It can be |
... |
arguments passed to the plot functions. Check arguments in |
sensemakr
The print and summary methods provide verbal descriptions of the sensitivity analysis results
obtained with the function sensemakr. The function ovb_minimal_reporting provides
latex or html code for a minimal
sensitivity analysis reporting, as suggested in Cinelli and Hazlett (2020).
## S3 method for class 'sensemakr' print(x, digits = max(3L, getOption("digits") - 2L), ...) ## S3 method for class 'sensemakr' summary(object, digits = max(3L, getOption("digits") - 3L), ...) ovb_minimal_reporting( x, digits = 3, verbose = TRUE, format = c("latex", "html", "pure_html"), ... )## S3 method for class 'sensemakr' print(x, digits = max(3L, getOption("digits") - 2L), ...) ## S3 method for class 'sensemakr' summary(object, digits = max(3L, getOption("digits") - 3L), ...) ovb_minimal_reporting( x, digits = 3, verbose = TRUE, format = c("latex", "html", "pure_html"), ... )
x |
an object of class |
digits |
minimal number of significant digits. |
... |
arguments passed to other methods. |
object |
an object of class |
verbose |
if 'TRUE', the function prints the LaTeX code with |
format |
code format to print, either |
The function ovb_minimal_reporting returns the LaTeX/HTML code invisibly in character form and also prints with
cat the LaTeX code. To suppress automatic printing, set verbose = FALSE.
Cinelli, C. and Hazlett, C. (2020), "Making Sense of Sensitivity: Extending Omitted Variable Bias." Journal of the Royal Statistical Society, Series B (Statistical Methodology).
# runs regression model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # runs sensemakr for sensitivity analysis sensitivity <- sensemakr(model, treatment = "directlyharmed", benchmark_covariates = "female", kd = 1:3) # print sensitivity # summary summary(sensitivity) # prints latex code for minimal sensitivity analysis reporting ovb_minimal_reporting(sensitivity)# runs regression model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # runs sensemakr for sensitivity analysis sensitivity <- sensemakr(model, treatment = "directlyharmed", benchmark_covariates = "female", kd = 1:3) # print sensitivity # summary summary(sensitivity) # prints latex code for minimal sensitivity analysis reporting ovb_minimal_reporting(sensitivity)
This function computes the (extreme) robustness value of a regression coefficient.
The extreme robustness value describes the minimum strength of association (parameterized in terms of partial R2) that omitted variables would need to have with the treatment alone in order to change the estimated coefficient by a certain amount (for instance, to bring it down to zero).
The robustness value describes the minimum strength of association (parameterized in terms of partial R2) that omitted variables would need to have both with the treatment and with the outcome to change the estimated coefficient by a certain amount (for instance, to bring it down to zero).
For instance, a robustness value of 1% means that an unobserved confounder that explain 1% of the residual variance of the outcome and 1% of the residual variance of the treatment is strong enough to explain away the estimated effect. Whereas a robustness value of 90% means that any unobserved confounder that explain less than 90% of the residual variance of both the outcome and the treatment assignment cannot fully account for the observed effect. You may also compute robustness value taking into account sampling uncertainty. See details in Cinelli and Hazlett (2020).
The functions robustness_value and extreme_robustness_value can take as input an lm object or you may directly pass the t-value and degrees of freedom.
rv is a shorthand wrapper for robustness_value.
xrv is a shorthand wrapper for extreme_robustness_value.
robustness_value(...) rv(...) ## S3 method for class 'lm' robustness_value( model, covariates = NULL, q = 1, alpha = 0.05, invert = FALSE, ... ) ## S3 method for class 'fixest' robustness_value( model, covariates = NULL, q = 1, alpha = 0.05, invert = FALSE, message = TRUE, ... ) ## Default S3 method: robustness_value(model, ...) ## S3 method for class 'numeric' robustness_value(t_statistic, dof, q = 1, alpha = 0.05, invert = FALSE, ...) extreme_robustness_value(...) xrv(...) ## S3 method for class 'lm' extreme_robustness_value( model, covariates = NULL, q = 1, alpha = 0.05, invert = FALSE, ... ) ## S3 method for class 'fixest' extreme_robustness_value( model, covariates = NULL, q = 1, alpha = 0.05, invert = FALSE, message = TRUE, ... ) ## Default S3 method: extreme_robustness_value(model, ...) ## S3 method for class 'numeric' extreme_robustness_value( t_statistic, dof, q = 1, alpha = 0.05, invert = FALSE, ... )robustness_value(...) rv(...) ## S3 method for class 'lm' robustness_value( model, covariates = NULL, q = 1, alpha = 0.05, invert = FALSE, ... ) ## S3 method for class 'fixest' robustness_value( model, covariates = NULL, q = 1, alpha = 0.05, invert = FALSE, message = TRUE, ... ) ## Default S3 method: robustness_value(model, ...) ## S3 method for class 'numeric' robustness_value(t_statistic, dof, q = 1, alpha = 0.05, invert = FALSE, ...) extreme_robustness_value(...) xrv(...) ## S3 method for class 'lm' extreme_robustness_value( model, covariates = NULL, q = 1, alpha = 0.05, invert = FALSE, ... ) ## S3 method for class 'fixest' extreme_robustness_value( model, covariates = NULL, q = 1, alpha = 0.05, invert = FALSE, message = TRUE, ... ) ## Default S3 method: extreme_robustness_value(model, ...) ## S3 method for class 'numeric' extreme_robustness_value( t_statistic, dof, q = 1, alpha = 0.05, invert = FALSE, ... )
... |
arguments passed to other methods. First argument should either be an |
model |
an |
covariates |
model covariates for which the robustness value will be computed. Default is to compute the robustness value of all covariates. |
q |
percent change of the effect estimate that would be deemed problematic. Default is |
alpha |
significance level. |
invert |
should IRV be computed instead of RV? (i.e. is the estimate insignificant?). Default is |
message |
should messages be printed? Default = TRUE. |
t_statistic |
|
dof |
residual degrees of freedom of the regression |
The function returns a numerical vector with the robustness value. The arguments q and alpha are saved as attributes of the vector for reference.
Cinelli, C. and Hazlett, C. (2020), "Making Sense of Sensitivity: Extending Omitted Variable Bias." Journal of the Royal Statistical Society, Series B (Statistical Methodology).
# using an lm object ## loads data data("darfur") ## fits model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) ## robustness value of directly harmed q =1 (reduce estimate to zero) robustness_value(model, covariates = "directlyharmed", alpha = 1) ## extreme robustness value of directly harmed q =1 (reduce estimate to zero) extreme_robustness_value(model, covariates = "directlyharmed", alpha = 1) ## note it equals the partial R2 of the treatment with the outcome partial_r2(model, covariates = "directlyharmed") ## robustness value of directly harmed q = 1/2 (reduce estimate in half) robustness_value(model, covariates = "directlyharmed", q = 1/2, alpha = 1) ## robustness value of directly harmed q = 1/2, alpha = 0.05 ## (reduce estimate in half, with 95% confidence) robustness_value(model, covariates = "directlyharmed", q = 1/2, alpha = 0.05) # you can also provide the statistics directly robustness_value(t_statistic = 4.18445, dof = 783, alpha = 1) extreme_robustness_value(t_statistic = 4.18445, dof = 783, alpha = 1)# using an lm object ## loads data data("darfur") ## fits model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) ## robustness value of directly harmed q =1 (reduce estimate to zero) robustness_value(model, covariates = "directlyharmed", alpha = 1) ## extreme robustness value of directly harmed q =1 (reduce estimate to zero) extreme_robustness_value(model, covariates = "directlyharmed", alpha = 1) ## note it equals the partial R2 of the treatment with the outcome partial_r2(model, covariates = "directlyharmed") ## robustness value of directly harmed q = 1/2 (reduce estimate in half) robustness_value(model, covariates = "directlyharmed", q = 1/2, alpha = 1) ## robustness value of directly harmed q = 1/2, alpha = 0.05 ## (reduce estimate in half, with 95% confidence) robustness_value(model, covariates = "directlyharmed", q = 1/2, alpha = 0.05) # you can also provide the statistics directly robustness_value(t_statistic = 4.18445, dof = 783, alpha = 1) extreme_robustness_value(t_statistic = 4.18445, dof = 783, alpha = 1)
This function performs sensitivity analysis to omitted variables as discussed in Cinelli and Hazlett (2020). It returns an object of
class sensemakr with several pre-computed sensitivity statistics for reporting.
After running sensemakr you may directly use the plot, print and summary methods in the returned object.
sensemakr(...) ## S3 method for class 'lm' sensemakr( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, q = 1, alpha = 0.05, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = "Manual Bound", reduce = TRUE, ... ) ## S3 method for class 'fixest' sensemakr( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, q = 1, alpha = 0.05, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = "Manual Bound", reduce = TRUE, ... ) ## S3 method for class 'formula' sensemakr( formula, method = c("lm", "feols"), vcov = "iid", data, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, q = 1, alpha = 0.05, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = "", reduce = TRUE, ... ) ## S3 method for class 'numeric' sensemakr( estimate, se, dof, treatment = "D", q = 1, alpha = 0.05, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = "manual_bound", r2dxj.x = NULL, r2yxj.dx = r2dxj.x, benchmark_covariates = "manual_benchmark", kd = 1, ky = kd, reduce = TRUE, ... )sensemakr(...) ## S3 method for class 'lm' sensemakr( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, q = 1, alpha = 0.05, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = "Manual Bound", reduce = TRUE, ... ) ## S3 method for class 'fixest' sensemakr( model, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, q = 1, alpha = 0.05, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = "Manual Bound", reduce = TRUE, ... ) ## S3 method for class 'formula' sensemakr( formula, method = c("lm", "feols"), vcov = "iid", data, treatment, benchmark_covariates = NULL, kd = 1, ky = kd, q = 1, alpha = 0.05, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = "", reduce = TRUE, ... ) ## S3 method for class 'numeric' sensemakr( estimate, se, dof, treatment = "D", q = 1, alpha = 0.05, r2dz.x = NULL, r2yz.dx = r2dz.x, bound_label = "manual_bound", r2dxj.x = NULL, r2yxj.dx = r2dxj.x, benchmark_covariates = "manual_benchmark", kd = 1, ky = kd, reduce = TRUE, ... )
... |
arguments passed to other methods. |
model |
An |
treatment |
A character vector with the name of the treatment variable of the model. |
benchmark_covariates |
The user has two options: (i) character vector of the names of covariates that will be used to bound the plausible strength of the unobserved confounders. Each variable will be considered separately; (ii) a named list with character vector names of covariates that will be used, as a group, to bound the plausible strength of the unobserved confounders. The names of the list will be used for the benchmark labels. Note: for factor variables with more than two levels, you need to provide the name of each level as encoded in the |
kd |
numeric vector. Parameterizes how many times stronger the confounder is related to the treatment in comparison to the observed benchmark covariate.
Default value is |
ky |
numeric vector. Parameterizes how many times stronger the confounder is related to the outcome in comparison to the observed benchmark covariate.
Default value is the same as |
q |
percent change of the effect estimate that would be deemed problematic. Default is |
alpha |
significance level. |
r2dz.x |
hypothetical partial R2 of unobserved confounder Z with treatment D, given covariates X. |
r2yz.dx |
hypothetical partial R2 of unobserved confounder Z with outcome Y, given covariates X and treatment D. |
bound_label |
label to bounds provided manually in |
reduce |
should the bias adjustment reduce or increase the
absolute value of the estimated coefficient? Default is |
formula |
an object of the class |
method |
the default is |
vcov |
the variance/covariance used in the estimation when using |
data |
data needed only when you pass a formula as first parameter. An object of the class |
estimate |
Coefficient estimate. |
se |
standard error of the coefficient estimate. |
dof |
residual degrees of freedom of the regression. |
r2dxj.x |
partial R2 of covariate Xj with the treatment D (after partialling out the effect of the remaining covariates X, excluding Xj). |
r2yxj.dx |
partial R2 of covariate Xj with the outcome Y (after partialling out the effect of the remaining covariates X, excluding Xj). |
An object of class sensemakr, containing:
info A data.frame with the general information of the analysis, including the formula used, the name of the treatment variable, parameter values such as q, alpha, and whether the bias is assumed to reduce the current estimate.
sensitivity_stats A data.frame with the sensitivity statistics for the treatment variable, as computed by the function sensitivity_stats.
bounds A data.frame with bounds on the strength of confounding according to some benchmark covariates, as computed by the function ovb_bounds.
Cinelli, C. and Hazlett, C. (2020), "Making Sense of Sensitivity: Extending Omitted Variable Bias." Journal of the Royal Statistical Society, Series B (Statistical Methodology).
The function sensemakr is a convenience function. You may use the other sensitivity functions of the package directly, such as the functions for sensitivity plots
(ovb_contour_plot, ovb_extreme_plot) the functions for computing bias-adjusted estimates and t-values (adjusted_estimate, adjusted_t),
the functions for computing the robustness value and partial R2 (robustness_value, partial_r2), or the functions for bounding the strength
of unobserved confounders (ovb_bounds), among others.
# loads dataset data("darfur") # runs regression model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # runs sensemakr for sensitivity analysis sensitivity <- sensemakr(model, treatment = "directlyharmed", benchmark_covariates = "female", kd = 1:3) # short description of results sensitivity # long description of results summary(sensitivity) # plot bias contour of point estimate plot(sensitivity) # plot bias contour of t-value plot(sensitivity, sensitivity.of = "t-value") # plot bias contour of lower limit of CI plot(sensitivity, sensitivity.of = "lwr") # plot bias contour of upper limit of CI plot(sensitivity, sensitivity.of = "upr") # plot extreme scenario plot(sensitivity, type = "extreme") # latex code for sensitivity table ovb_minimal_reporting(sensitivity)# loads dataset data("darfur") # runs regression model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) # runs sensemakr for sensitivity analysis sensitivity <- sensemakr(model, treatment = "directlyharmed", benchmark_covariates = "female", kd = 1:3) # short description of results sensitivity # long description of results summary(sensitivity) # plot bias contour of point estimate plot(sensitivity) # plot bias contour of t-value plot(sensitivity, sensitivity.of = "t-value") # plot bias contour of lower limit of CI plot(sensitivity, sensitivity.of = "lwr") # plot bias contour of upper limit of CI plot(sensitivity, sensitivity.of = "upr") # plot extreme scenario plot(sensitivity, type = "extreme") # latex code for sensitivity table ovb_minimal_reporting(sensitivity)
Convenience function that computes the robustness_value,
partial_r2 and partial_f2 of the coefficient of interest.
sensitivity_stats(...) ## S3 method for class 'lm' sensitivity_stats( model, treatment, q = 1, alpha = 0.05, reduce = TRUE, invert = FALSE, ... ) ## S3 method for class 'fixest' sensitivity_stats( model, treatment, q = 1, alpha = 0.05, reduce = TRUE, invert = FALSE, message = T, ... ) ## S3 method for class 'numeric' sensitivity_stats( estimate, se, dof, treatment = "treatment", q = 1, alpha = 0.05, reduce = TRUE, invert = FALSE, ... )sensitivity_stats(...) ## S3 method for class 'lm' sensitivity_stats( model, treatment, q = 1, alpha = 0.05, reduce = TRUE, invert = FALSE, ... ) ## S3 method for class 'fixest' sensitivity_stats( model, treatment, q = 1, alpha = 0.05, reduce = TRUE, invert = FALSE, message = T, ... ) ## S3 method for class 'numeric' sensitivity_stats( estimate, se, dof, treatment = "treatment", q = 1, alpha = 0.05, reduce = TRUE, invert = FALSE, ... )
... |
arguments passed to other methods. |
model |
An |
treatment |
A character vector with the name of the treatment variable of the model. |
q |
percent change of the effect estimate that would be deemed problematic. Default is |
alpha |
significance level. |
reduce |
should the bias adjustment reduce or increase the
absolute value of the estimated coefficient? Default is |
invert |
should IRV be computed instead of RV? (i.e. is the estimate insignificant?). Default is |
message |
should messages be printed? Default = TRUE. |
estimate |
Coefficient estimate. |
se |
standard error of the coefficient estimate. |
dof |
residual degrees of freedom of the regression. |
A data.frame containing the following quantities:
a character with the name of the treatment variable
a numeric vector with the estimated effect of the treatment
a numeric vector with the estimated standard error of the treatment effect
a numeric vector with the t-value of the treatment
a numeric vector with the partial R2 of the treatment and the outcome, see details in partial_r2
a numeric vector with the robustness value of the treatment, see details in robustness_value
a numeric vector with the robustness value of the treatment considering statistical significance, see details in robustness_value
a numeric vector with the partial (Cohen's) f2 of the treatment with the outcome, see details in partial_f2
a numeric vector with the degrees of freedom of the model
Cinelli, C. and Hazlett, C. (2020), "Making Sense of Sensitivity: Extending Omitted Variable Bias." Journal of the Royal Statistical Society, Series B (Statistical Methodology).
## loads data data("darfur") ## fits model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) ## sensitivity stats for directly harmed sensitivity_stats(model, treatment = "directlyharmed") ## you can also pass the numeric values directly sensitivity_stats(estimate = 0.09731582, se = 0.02325654, dof = 783)## loads data data("darfur") ## fits model model <- lm(peacefactor ~ directlyharmed + age + farmer_dar + herder_dar + pastvoted + hhsize_darfur + female + village, data = darfur) ## sensitivity stats for directly harmed sensitivity_stats(model, treatment = "directlyharmed") ## you can also pass the numeric values directly sensitivity_stats(estimate = 0.09731582, se = 0.02325654, dof = 783)