How to use PLM model get the LETTER GROUP like this?

[ZHEYA]

I have three variables and want to get results with different interactions. But I cannot get each effect with the letter group. The below showed was used PROC mix model with repeat measurement. But now I don't have repeat measures. I can only use liner model.

Effect=Biosolid   Method=LSD(P<.05)   Set=1

Obs	Biosolid	IS	TIME	Estimate	Standard Error	Letter Group
1	UREA		_	10778	539.68	A
2	ATB+U		_	7327.77	539.68	B
3	ATB		_	7104.96	539.68	B
4	CONTROL		_	4201.30	539.68	C

[ballardw]

As a minimum show the code you have attempted. Better is to provide example data in the form of data step code pasted into a text box opened on the forum with the </> icon above the main message window.

Since you mention PLM, that implies that you have created an item store as output from some other procedure.

If this variable is used in a procedure as a class variable most of the output is going to be in the form of differences /comparisons to a reference level specified in the code. So you need to start with the input data and code for that procedure.

Note: if the interaction did not exist in the base model data you can't ask for a result involving that interaction in PLM either.