To cite ROCR in publications use:

  Sing T, Sander O, Beerenwinkel N, Lengauer T (2005). “ROCR:
  visualizing classifier performance in R.” _Bioinformatics_, *21*(20),
  7881. <http://rocr.bioinf.mpi-sb.mpg.de>.

A BibTeX entry for LaTeX users is

  @Article{,
    entry = {article},
    title = {ROCR: visualizing classifier performance in R},
    author = {T. Sing and O. Sander and N. Beerenwinkel and T. Lengauer},
    year = {2005},
    journal = {Bioinformatics},
    volume = {21},
    number = {20},
    pages = {7881},
    url = {http://rocr.bioinf.mpi-sb.mpg.de},
  }

We have invested a lot of time and effort in creating ROCR, please cite
it when using it for data analysis.