1. Which of the following possibilities is a concern with a repeated-measures study? a. Negative values for the difference scores b. Carry-over effects c. Obtaining a mean difference that is due to individual differences rather than treatment differences d. All of the other options are major concerns. 3. b A researcher conducts an experiment comparing INO treatment conditions with 15 scores in each treatment condition. * b. If a repeated-measures design is used, how many subjects are needed for the experiment