What is the meaning of different RESIDUAL positions in the PROC GLIMMIX' RANDOM statement ?

[stan]

Folks:

here are the examples:

RANDOM <my_variable1> / RESIDUAL SUBJECT = <my_variable2>;

and

RANDOM _RESIDUAL_ / SUBJECT = <my_variable2>;

Thank you.

[SteveDenham]

The former syntax specifies an R side covariance structure for <my_variable1>, while the latter syntax models an overdispersion.  I believe that since the default type is TYPE=VC, the two statements as they currently stand should yield the same results.  If not, please post, as this is a potentially interesting event.

Steve Denham

[stan]

Steve, at first glance the outputs are the same. I also met another explanation by @lvm:

If you do not have missing values for trial (i.e., same trials for each subject), you can use:
RANDOM _RESIDUAL_ / SUBJECT=SUB TYPE=CS;

Probably this is the same you mention.