If I knew the math better for b-splines, I could just calculate the variables contribution to the link function.  Perhaps I should be reading more about that. -Seth ... View more

Hi, I have similar problem. I have over 300 clusters, where sizes of clusters varied from 1 (there are many totally independent subjects) to 250 of individuals with total of over 5000 individuals. I have already obtained correlation matrix between indiviuals using R for each of the clusters. I would like to used PROC GENMOD in SAS and use my own correlation structure instead of using say, EXCH for each cluster. There is an option for userdefined matrix in SAS for a single matrix, but how would I specify these several matrices for these clusters? Also, how do I make sure that the SAS picks up the correct correlation between any two individuals from my data in the GENMOD analysis? Is there any way to specify user defined correlation matrix of all individuals in GENMOD without spefifying clustering variable? Many thanks in advance. BNO. ... View more

Thanks Dale. I was taking the idea of a likelihood ratio test and applying it to a joint hypothesis test on the parameter estimates. With the likelihood ratio test, you would fit two models and so there would be two different covariance structures. This would not be the case with a joint hypothesis test, as they work on different concepts (as far as my current level of understanding). So, my last bit was indeed nonsensical! Seth ... View more