Dear Rafael, The line below had one closing bracket to much. The line below should work.
am2 <- lmer(dv ~ myfactor + (1|subject), data = mydata) Furthermore I would advise to change myfactor for a character variable to a factor. HTH, Thierry ------------------------------------------------------------------------ ---- ir. Thierry Onkelinx Instituut voor natuur- en bosonderzoek team Biometrie & Kwaliteitszorg Gaverstraat 4 9500 Geraardsbergen Belgium Research Institute for Nature and Forest team Biometrics & Quality Assurance Gaverstraat 4 9500 Geraardsbergen Belgium tel. + 32 54/436 185 thierry.onkel...@inbo.be www.inbo.be To call in the statistician after the experiment is done may be no more than asking him to perform a post-mortem examination: he may be able to say what the experiment died of. ~ Sir Ronald Aylmer Fisher The plural of anecdote is not data. ~ Roger Brinner The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. ~ John Tukey > -----Oorspronkelijk bericht----- > Van: r-help-boun...@r-project.org > [mailto:r-help-boun...@r-project.org] Namens Rafael Diaz > Verzonden: maandag 5 juli 2010 3:37 > Aan: r-help@r-project.org > Onderwerp: [R] repeated measures with missing data > > Dear R help group, I am teaching myself linear mixed models > with missing data since I would like to analyze a stats > design with these kind of models. The textbook example is for > the procedure "proc MIXED" in SAS, but I would like to know > if there is an equivalent in R. This example only includes > two time-measurements across subjects (a t-test "with missing > values"), but I will need to to this with three > time-measurements (repeated measures ANOVA with missing values): > > Patient Treatment > A B > > > 1 20 12 > 2 26 24 > 3 16 17 > 4 29 21 > 5 22 N/A > 6 N/A 12 > > I have tried this analysis using using the instructions below > with the help of "Mixed-Effects Models in S and S-Plus", but > have not been able to go around the missing data issue as follows: > > tmtA <- c(20,26, 16,29,22,NA) > tmtB <- c(12,24,17,21,NA,17) > require(lme4) > dv <- c(20,12,26,24,16,17,29,21,22,17) > subject <- rep(c("s1","s2","s3","s4","s5","s6"),each=2) > subject <- subject[-c(10,11)] > myfactor <- rep(c("f1","f2"), 6) > myfactor <- myfactor[-c(10,11)] > mydata <- data.frame(dv, subject, myfactor) > am2 <- lmer(dv ~ myfactor + (1|subject)), data = mydata) > summary(am2) > anova(am2) > subject <- subject[-c(10,11)] > > > Any help would be greatly appreciated. Thank you, > > Rafael Diaz > Assistant Professor > Math and Stats Dept > California State University Sacramento > > > > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. > Druk dit bericht a.u.b. niet onnodig af. Please do not print this message unnecessarily. Dit bericht en eventuele bijlagen geven enkel de visie van de schrijver weer en binden het INBO onder geen enkel beding, zolang dit bericht niet bevestigd is door een geldig ondertekend document. The views expressed in this message and any annex are purely those of the writer and may not be regarded as stating an official position of INBO, as long as the message is not confirmed by a duly signed document. ______________________________________________ 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.
