Dear All,
  Sorry if this question may not be appropriate to this list. I have the following question about the significance of effects in NLME. I fitted data with nlme using  the SSlogis as a  specification for the conditional mean of my dependent variable Y. When xmid and scal were considered as random,  my covarite of interest X was found to have a significant effect on xmid but not on scal. However, when I assume that only xmid is random, the effect of my covariate X was found to have a significant effect on both xmid and scal. Of course the AIC and the residuals were both smaller in the firts model. Thus my question: Which model should I select: the one that  fits  better to the data (i.e Model 1) or the one that shows significant effects of my covariate (Model2). Or in another way, Is it legitimate to use model 2?
   
  Many thanks in advance,
   
  Bernard
   
   

             
---------------------------------

	[[alternative HTML version deleted]]

