Dear list, I am using the lme funcion to fit a mixed model for the time response of a number of physiological variables. The random variable would be the individual on which physiological variables are measured at different time points. I have 4 time points, 5 individuals and 3 replicates per condition (time/individual), and I would like to fit a quadratic model on time. The model I am using is
mm <- lme(myvar ~ time + time2, random= ~ time|individual,
data=clinical) being time2 = time*time I have a number of questions 1) I am not very sure the random effect is correctly modeled. Would I need to include the time2 variable aswell? 2) I would like to extract the F statistics of the model, and I do not find a function for this. Is this possible? 3) depending of the variable I take, I frequently obtain a convergence error as a result of the lme funcion. Any ideas on what to do to improve convergence? Thank you Ana Conesa, PhD Centro de Investigacion Principe Felipe Avda. Autopista Saler 16 46013 Valencia http://bioinfo.cipf.es