I have run a glm with a final formula of : (dependent variable = parasite load, main effects are sex, month, length and weight, with sex:month and length:weight first order interactions).
I am using the summary(mod) command to give me the contrasts, which I believe use the contr.treatment command. I do not have a treatment group as such as I am comparing data from a wild system so I use the relevel command to reorder my factors in order to check the difference between each level and every other. I then use the coefficients and their related p-values to assess whether each level of my factors is significantly different from the next. This is fine for most things but what I really want to do is to assess whether there is a significant difference of between males and females in any particular month. However, because of my interaction term the male and female for any particular month are always the missing coefficients and so I can't contrast them with one another. Is there a way (preferably a relatively simple way) for me to do this. You will probably realise from my description above that I am a biologist not a statistician, so if anyone can help me in plain English that would be an enormous help. -- View this message in context: http://www.nabble.com/GLM-contrasting-question-tp25226439p25226439.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org 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.