In the study in question 4, everyone in my evening class was assigned to one condition and everyone in my day session class to the other. For this reason, the study may have had a problem in:...

In the study in question 4, everyone in my evening class was assigned to one condition and everyone in my day session class to the other.  For this reason, the study may have had a problem in:

1. convergent validity


2. interrater reliability


3. construct validity


4. internal validity