Thanks so much, Richard. That works. Hanna 2017-03-12 14:31 GMT-04:00 Richard M. Heiberger <r...@temple.edu>:
> I think you need either > > mod4 <- lm( y ~ -1 + area / (month*group), data=two) > > mod5 <- lm( y ~ area / (month*group), data=two) > > With either of those, area:month and area:group and Residuals add up. > > > On Sun, Mar 12, 2017 at 10:39 li li <hannah....@gmail.com> wrote: > >> 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. >> > [[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.
