Hi All, I have a dataset which contains 4 variables: area, group, time, y, Area is a factor that has two levels A and B, group is a factor that is nested within area. There are four groups within each area. y is the response variable, and time refers to different days.
Below is the how data looks like. First, I fit separate ancova for each area (area A and B), For each area, I obtained different regression lines for each group within that area. mod1 <- lm(y ~ month * group, data=two[two$area=="A"] mod2 <- lm(y ~ month * group, data=two[two$area=="B"] I want to fit the model at one time by using the nested structure mod3 <- lm(y ~ -1+ month * (area/group), data=two) I get different results using mod 3 from using mod1 and mod2. Can someone give some suggestion on this. How can I specify the model in R to simultaneously fit the model to get the same results as from mod1 and mod2. Thanks very much! Hanna > head(two[two$area=="A",]) group time y area 79 1 3 -1.394327 A 80 1 6 -1.435485 A 81 1 9 -1.406497 A 82 1 12 -1.265848 A 83 1 0 -1.316768 A 84 1 6 -1.431292 A> head(two[two$area=="B",]) group time y area 1 1 0 -2.145581 B 2 1 0 -1.910543 B 3 1 0 -2.128632 B 4 1 3 -2.079442 B 5 1 3 -2.273026 B 6 1 6 -2.312635 B [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.