UCBAdmissions              package:base              R Documentation

Student Admissions at UC Berkeley

Description:

     Aggregate data on applicants to graduate school at Berkeley for
     the six largest departments in 1973 classified by admission and
     sex.

Usage:

     data(UCBAdmissions)

Format:

     A 3-dimensional array resulting from cross-tabulating 4526
     observations on 3 variables.  The variables and their levels are
     as follows:

       No  Name    Levels
        1  Admit   Admitted, Rejected
        2  Gender  Male, Female
        3  Dept    A, B, C, D, E, F

Details:

     This data set is frequently used for illustrating Simpson's
     paradox, see Bickel et al. (1975).  At issue is whether the data
     show evidence of sex bias in admission practices.  There were 2691
     male applicants, of whom 1198 (44.5%) were admitted, compared with
     1835 female applicants of whom 557 (30.4%) were admitted.  This
     gives a sample odds ratio of 1.83, indicating that males were
     almost twice as likely to be admitted.  In fact, graphical methods
     (as in the example below) or log-linear modelling show that the
     apparent association between admission and sex stems from
     differences in the tendency of males and females to apply to the
     individual departments (females used to apply ``more'' to
     departments with higher rejection rates).

     This data set can also be used for illustrating methods for
     graphical display of categorical data, such as the general-purpose
     mosaic plot or the ``fourfold display'' for 2-by-2-by-k tables. 
     See the home page of Michael Friendly (<URL:
     http://hotspur.psych.yorku.ca/SCS/friendly.html>) for further
     information.

References:

     Bickel, P. J., Hammel, E. A., and O'Connell, J. W. (1975) Sex bias
     in graduate admissions: Data from Berkeley. Science, 187, 398-403.

Examples:

     data(UCBAdmissions)
     ## Data aggregated over departments
     apply(UCBAdmissions, c(1, 2), sum)
     mosaicplot(apply(UCBAdmissions, c(1, 2), sum),
                main = "Student admissions at UC Berkeley")
     ## Data for individual departments
     opar <- par(mfrow = c(2, 3), oma = c(0, 0, 2, 0))
     for(i in 1:6)
       mosaicplot(UCBAdmissions[,,i],
         xlab = "Admit", ylab = "Sex",
         main = paste("Department", LETTERS[i]))
     mtext(expression(bold("Student admissions at UC Berkeley")),
           outer = TRUE, cex = 1.5)
     par(opar)

