These data are available at
http://data.princeton.edu/multilevel/guImmun.dat. Multiple
indicator columns in the original data table have been collapsed to
factors for this data frame.
References
Rodriguez, Germ�n and Goldman, Noreen (1995), "Improved estimation
procedures for multilevel models with binary response: a case-study",
Journal of the Royal Statistical Society, Series A, 164,
339-355.