The methodology used in cvscores() is an extension of that described in Maindonald and Burden (2005)

Maindonald, J.H. and Burden, C.J., 2005. Selection bias in plots of microarray or other data that have been sampled from a high-dimensional space. In R. May and A.J. Roberts, eds., Proceedings of 12th Computational Techniques and Applications Conference CTAC-200, volume 46, pp. C59--C74.

Corresponding BibTeX entry:

  @InProceedings{,
    title = {Selection bias in plots of microarray or other data that
      have been sampled from a high-dimensional space},
    journal = {Australian {&} New Zealand Industrial and Applied
      Mathematics Journal},
    volume = {46},
    pages = {C59--C74},
    year = {2005},
    booktitle = {Proceedings of 12th Computational Techniques and
      Applications Conference CTAC-2004},
    editor = {Rob May and A. J. Roberts},
    author = {{Maindonald} and {J.H.} and {Burden} and {C.J.}},
    url = {http://anziamj.austms.org.au/V46/CTAC2004/Main},
  }