The SOLUTION option in MODEL statement of PROC MIXED will provide the slopes. ... View more

By "long", I presume you mean a dataset with possible repeats of the by variable ID.  And by "wide" do you mean one observation per ID?   If so then your program will be a "LONG left join WIDE on long.id=wide.id" in proc sql syntax. ... View more

Just guessing here, but because extraversionnew and sample are both crossed with time, it may be that you have something like complete collinearity between some of the variables in your model.  The other possibility is that you are overfitting your available data.   Steve Denham ... View more