Dear Lihong,

Simply use a model of the form:

  Subject effects: GroupA, GroupB, ControlVariable1, ControlVariable2, ControlVariable3

  Between-subjects contrast: [1 -1 0 0 0]

  Conditions: Pre, Post

  Between-conditions contrast: [-1 1]

From your design plot it seems you were using instead a model of the form:

  Subject effects: GroupA, GroupB, ControlVariable1, ControlVariable2, ControlVariable3

  Between-subjects contrast: [1 -1 0 0 0]

  Conditions: Pre, Post

  Between-conditions contrast: [1 0; 0 1]

Hope this helps

Alfonso

Originally posted by Lihong Wang:

Dear Alfoso,

How can I check the F or T of the group x intervention interaction effect? 

 

Thank you,

--Lihong