Hello, I'm trying to use NLME for a non-linear model with one random effect that is the same as the one grouping level (chamber). Using the following statement:
test <- nlme(flux ~ b0 * exp((b1*soiltemp) - (b2*soiltemp^2)) * vpd^b3 * mstsoil2^b4 * airtemp^b5, data = ac5, fixed = list(b0 + b1 + b2 + b3 + b4 + b5 ~ 1), random = chamber ~ 1, start = c(b0 = 570, b1 = 0.08, b2 = 0.002, b3 = -0.06, b4 = 3, b5 = 0.3), subset = airtemp > 0) I always get the error message "Error in eval(expr, envir, enclos) : object 'chamber' not found" Data "ac5" is a groupedData object with chamber as the grouping factor: head(ac5) Grouped Data: flux ~ soiltemp + vpd + mstsoil2 + airtemp | chamber I've tried many variations such as random = list(chamber ~ 1) or adding the "groups" statement or trying to put chamber on the RHS of the model statement, after the fixed effects, but I always get the same error message. What is the correct way to formulate the call to nlme? Thank you in advance. Toby Gass tobygass at cnr dot colostate dot edu ______________________________________________ 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.
