Dr. F. did a study and obtained significant results. The more varied their participants in such charac­teristics as age, ethnic group etc., the more limited the potential generalizations of his study...

Dr. F. did a study and obtained significant results.  The more varied their participants in such charac­teristics as age, ethnic group etc.,

1. the more limited the potential generalizations of his study


2. the better the internal validity of his study


3. the greater the external validity of his study


4. the less representative his sample