The data are from a randomized clinical trial to compare a test treatment to placebo for skin conditions, and listings of the data appear in Stanish, Gillings, Koch (1978a, b). The variables are as follows:
data(skin)A data frame with 172 observations and 6 variables.
centera factor vector for two centers
treata factor with levels A and P for active and placebo treatments, skinectively
stagea numeric vector for initial severity of the skin condition according to 3 categories (3 = fair, 4 = poor, 5 = exacerbation) at baseline measurement
res1a numeric vector for extent of improvement at visit 1 according to 5 categories (1 = rapidly improving, 2 = slowly improving, 3 = stable, 4 = slowly worsening, 5 = rapidly worsening)
res2a numeric vector for extent of improvement at visit 2 with same categories as res1
res3a numeric vector for extent of improvement at visit 3 with same categories as res1
Stanish W, Gillings D, Koch G (1978a). "An application of multivariate ratio methods for the analysis of a longitudinal clinical trial with missing data." Biometrics, 34(2), pp. 305--317.
Stanish WM, Koch GG, Landis JR (1978b). "A computer program for multivariate ratio analysis (MISCAT)." Computer Programs in Biomedicine, 8(3-4), 197--207.