Changes in version 0.1.0                        

Initial release.

stagelife implements the stage life testing (SLT) model of Laumen &
Cramer (2019), "Stage life testing", Naval Research Logistics
66(8):632-647, doi:10.1002/nav.21874 -- a two-stage cumulative-exposure
life-testing model in which units begin on a baseline stress and, at a
fixed change-point, some or all surviving units move to an elevated
stress.

  - Twelve baseline lifetime distributions (Weibull, Power Lindley,
    Exponentiated Lindley, Exponentiated Exponential, Marshall-Olkin
    Exponential, Lomax, Exponentiated Teissier, Log-Logistic, Chen,
    Log-normal, Gamma, and Power Muth), each with closed-form density,
    distribution, and quantile functions.
  - Three parameter-sharing cases (common, shape1, shape11) for the
    elevated-stage shape parameter.
  - Data generation under the random-withdrawal design, with both
    fixed-proportion and fixed-count selection rules, via rslt(); the
    classical simple-step-stress design is the prop_transfer = 1 special
    case.
  - Maximum likelihood estimation via fit_slt(), with standard print(),
    summary(), coef(), vcov(), logLik(), AIC(), and BIC() methods.
  - Asymptotic (Wald) and bootstrap (non-parametric and parametric;
    percentile, bootstrap-t, and log-scale bootstrap-t) confidence
    intervals.
  - Design-planning tools (slt_prob_stage1()), Kolmogorov-Smirnov
    goodness-of-fit testing with a parametric-bootstrap correction
    (slt_gof_ks()), likelihood-ratio tests between nested cases
    (slt_lrt()), and AIC/BIC model comparison across fits
    (slt_model_comparison()).
  - Diagnostic plots: fitted CDF, survival, P-P, and Q-Q.
  - Four bundled real step-stress data sets.

See vignette("stagelife-intro") for a full worked example.