Hello all, I have arranged my data as per Dennis's suggestion in this post http://www.mail-archive.com/r-help@r-project.org/msg107156.html. the posted code works fine but when I try to apply it to my data, i get "> u2 <- ddply(xxm, .(plateid, cytokine), as.data.frame.function(f)) Error in t.test.formula(conc ~ Self_T1D, data = df, na.rm = T) : grouping factor must have exactly 2 levels". Self_T1D has two levels "N" and "Y"
I have used the ddply function to do the mean and sd for the same dataframe without any issues. I would appreciate help to solve this. Thanks Sharad -- View this message in context: http://r.789695.n4.nabble.com/error-for-ttest-tp3448056p3448056.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.
