Hi, I'm facing two difficulties... *The first one:* I'm trying to estimate a survey weighted Gamma Regression with log link, but I found out that Zelig inform just the results for the inverse link. Adding "family=Gamma(link=log)" does not work. See the example below: install.packages("Zelig") require(Zelig) #Loading data data(api, package = "survey") # Gamma inverse z.inverse <- zelig(api00 ~ meals + yr.rnd + as.factor(awards), model = "gamma.survey", weights = ~pw, data = apistrat, family=Gamma(link=inverse)) # Gamma log z.log <- zelig(api00 ~ meals + yr.rnd + as.factor(awards), model = "gamma.survey", weights = ~pw, data = apistrat, family=Gamma(link=log)) #comparison coefficients(z.inverse) == coefficients(z.log) *#inverse-link and log-link coefficients must be different, but they are not* * (Intercept) meals yr.rndYes as.factor(awards)Yes * * TRUE TRUE TRUE TRUE * ######################### g.inverse <- glm(api00 ~ meals + yr.rnd + as.factor(awards), weights = pw, data = apistrat, family=Gamma(link="inverse")) g.log <- glm(api00 ~ meals + yr.rnd + as.factor(awards), weights = pw, data = apistrat, family=Gamma(link="log")) #comparison coefficients(g.inverse) == coefficients(g.log) *#glm brings the correct results* * (Intercept) meals yr.rndYes as.factor(awards)Yes * * FALSE FALSE FALSE FALSE * *The second one:* I'm not getting the output for setx in any model! Not even for "model='ls' " # In the example above: meals_seq=seq(from=1,to=30,by=1) setx(z.inverse, meals=meals_seq) *Call:* *NULL* *Model name = * *Formula = NULL* *Complete data.frame:* *NULL* *Model Matrix (Design Matrix):* *NULL* I'm using R 3.0.2 and Zelig 4.2-1. Rolling back to Zelig 3.5.4 is not worth in this case... setx works fine in that version, but "gamma.survey" does not. thanks in advance, Rogério J Barbosa Universidade de São Paulo, Brazil