Most sports injuries are immediate and obvious, like a broken leg. However, some can be more subtle, like the neurological damage that may occur when soccer players repeatedly head a soccer ball. To examine effects of repeated heading, McAllister et al. (2013)

examined a group of football and ice hockey players and a group of athletes in noncontact sports before and shortly after the season. The dependent variable was performance on a conceptual thinking task. Following are hypothetical data from an independent-measures study similar to the one by McAllister et al. The researchers measured conceptual thinking for contact and noncontact athletes at the beginning of their first season and for separate groups of athletes at the end of their second season.

a. Use a two-factor ANOVA with a 5 .05 to evaluate the main effects and interaction.

b. Calculate the effects size (h2

) for the main effects and the interaction.

c. Briefly describe the outcome of the study.
Factor B: Time Before the First Season After the Second Season Factor A:
Sport Contact Sport n = 20 n = 20 M = 9 M = 4 T = 180 T = 80 SS = 380 SS = 390 Noncontact Sport n = 20 n = 20 M = 9 M = 8 T = 180 T = 160 SS = 350 SS = 400 ΣX2 = 6360