Guest Session: 1 Question Remaining. Create Account to save progress.
Login
Data Collectionmedium
0:00.0

A researcher randomly assigns 150 participants to either a new cognitive training program (n=75n=75n=75) or control (n=75n=75n=75). Despite randomization, baseline measurements show:

  • Training group: mean age = 52 years, 68% female
  • Control group: mean age = 48 years, 45% female

After the training period, the training group shows significantly higher cognitive scores.

Which statement best describes a threat to internal validity?