A tennis instructor compared two homework methods. She took beginning students at her tennis camp and matched them in pairs in terms of their tennis abilities. She then randomly assigned the players to two conditions. Those in the control condition had to practice for half an hour every day with another player. Those in the experimental condition had to practice against a wall for half an hour every day. After two weeks of practice, the instructor measured how often each player could hit targets in different locations on the tennis court. The higher the percentage, the better the player had become.

Given the results below, interpret the study:

• MC = 48.00, ME = 57.00, N = 12, sD = 6.00

• sMD = 1.73, t = 5.20, 95%CIμDiff = [5.19, 12.81]