Hello All R Users, Function loglm() in library MASS can be cajoled to accomodate structural zeros in a cross-classification table. An example from Fienberg demonstrates how this can be done.
My question is: Can the function glm() perform the same task? Can glm() estimate a log-linear model with fixed zeros like loglm()? Thanks for your help, Andrew ## Fienberg, The Analysis of Cross-Classified Contingency Tables, 2nd ed., p.148. ## Results from survey of teenagers regarding their health concerns. health <- data.frame(expand.grid(CONCERNS = c("sex", "menstral", "healthy", "nothing"), AGE = c("12-15", "16-17"), GENDER = c("male", "female")), COUNT = c(4, 0, 42, 57, 2, 0, 7, 20, 9, 4, 19, 71, 7, 8, 10, 21)) health <- xtabs(COUNT ~ CONCERNS + AGE + GENDER, data = health) zeros <- data.frame(expand.grid(CONCERNS = c("sex", "menstral", "healthy", "nothing"), AGE = c("12-15", "16-17"), GENDER = c("male", "female")), COUNT = c(1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)) zeros <- xtabs(COUNT ~ CONCERNS + AGE + GENDER, data = zeros) library(MASS) fm.1 <- loglm(~ CONCERNS + AGE + GENDER, data = health, start = zeros, fitted = TRUE) fm.1; round(fm.1$fitted, 1) ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.