I'm a new user of nlme package and I don't know what formula I have to use for two models. 1.- If I have two grouping factors at the same level, what is the formula I have to use? For example, I have a Latin square design in which the factor is fixed and the rows and columns are random, y = factor + row + column + error following the formula for a randomized block design, I would use something like: lme(y~factor, random= ~ 1 | (row+column)) of course, the "+" is not accepted in that place but all the forms I find take one of the grouping factors nested in the other. 2.- I have one fixed factor (A) and a random one (B) nested in the fixed one. The formula: lme(y~A, random = ~ 1 | B) take B as a block, and of course is (I think) wrong, but the formula: lme(y~A, random = ~1 | A/B) gives a level of grouping more than I want. Is it possible put something like "B %in% A" as a grouping factor? Sorry if questions have no sense, but I've been shearching in nlme help and Pinheiro & Bates's book and I don't know if the function lme can handle these problems. Thanks for any hint, Eusebio Arenal -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._