search for: primary1

...When creating a groupedData object from a data.frame, you need to enter a function of the form: response ~primary|grouping Does this display function serve any purpose later on when specifying the model in the call to lme? If so, how would I include more terms in primary or grouping (I tried primary1+primary2+... as per one post in the archives, but it didn't work). If not, is it just for purposes of displaying the data? Thanks much, Scott Rifkin

In the non linear mixed effects package a groupedData object can be created to facilitate modeling. The gD object includes a formula of the form 'response variable' ~ 'primary covariate' | 'grouping factor'. In experiments creating response surfaces there are 2 or more primary covariates. Is there any way to use the groupedData() function to include 2 primary