I made some progess:
If I go: Analyze --> Mixed --> Linear
- skip the first window (LMM: specificy subjects and repeated)
- In the second window (LMM):
1) Dependent variable: blood glucose
2) Factors: treatment (treatment), time and participant number (id)
1) Button Fixed:
Enter in the model: treatment, time and treatment*time
2) Button Random:
This will result in data that give me the correct interaction values (same as with rANOVA and ANOVA of change)
However, it also gives a value for a time effect. But I want that value to be seperate for the control and the treatment group. I can archieve this by going to DATA --> SPLIT FILE --> organize output by groups: treatment. Then it gives the proper values for time effects, but it no longer gives an interaction value for the whole group. Is this a problem or is it ok to look up those values in seperate analysis?
Another question, is it a problem to do a LMM when you have a nonrandomized design, because you select subjects as a random factor?
Thanks in advance!