The first model uses a linear main-effects model: Hohe=Zeile Spalte Variante Notice that the Schnitt variable is not included in this model. Instead, the analysis is performed for each level of the Schnitt variable (because of the BY statement).    The second model includes interactions between variables. The '*' is used to include the interaction term between the variables and the Schnitt variable:  Hohe=Zeile Spalte Variante Zeile*Schnitt Spalte*Schnitt Variante*Schnitt Schnitt. (See the doc for how to specify effects on the MODEL statement.) Because the Schnitt variable is in the model, you can compare how different values of the Schnitt variable affect the response variable.   The REPEATED statement (see the doc) enables you to model the fact that each subject in the study contributed multiple observations. Most likely, responses from the same subject are correlated. The REPEATED statement tries to account for the fact that the responses are not independent. ... View more