Unlike proc logistic, proc mixed uses an over-parameterized model without much flexibility on adjusting for design matrix. But you are still able to mange the parameterization through ORDER= option in PROC MIXED statement. In your situation, you can do things like:You may think it is not worth to do the manipulation when there is only such a little convenience gained from changing the default level. That is what I am thinking at least.
JingJu

谢谢！

谢谢！

谢谢！

thank you ! i think your idea is very good.

不好意思，没做过这个东东