#### Berkeley Admissions Example: a 2x2x6 table #### let X=sex, Y=admission status, Z=department library(survival) library(vcd) #### data available as an array in R admit <- UCBAdmissions dimnames(admit) <- list( Admit=c("Admitted","Rejected"), Sex=c("Male","Female"), Dept=c("A","B","C","D","E","F")) admit #### create a flat contingency table ftable(admit, row.vars=c("Dept","Sex"), col.vars="Admit") ### conditional odds ratios XY.Z <- oddsratio(admit) # log scale exp(XY.Z$coef) exp(confint(XY.Z)) plot(XY.Z) ### Cochran-Mantel-Haenszel test of conditional independence mantelhaen.test(admit) mantelhaen.test(admit, correct=FALSE) ### marginal tables and odds ratios XY <- margin.table(admit, c(2,1)) ZY <- margin.table(admit, c(3,1)) XZ <- margin.table(admit, c(2,3)) oddsratio(XY, log=FALSE) exp(confint(oddsratio(XY))) chisq.test(XY, correct=FALSE) #source(file.choose()) # choose breslowday.test_.R breslowday.test(admit)