Due to recent concerns about player concussions, football helmets have recently increased in both size and mass. Have these changes made a difference? The article “The Effects of Helmet Weight on Hybrid III Head and Neck Responses by Comparing Unhelmeted and Helmeted Impacts” (J. Biomech. Engr. 2016) reports on an experiment in which repeated impact trials were performed on an artificial human head both wearing and not wearing a football helmet.

a. The following summary information for the variable head acceleration (g) is consistent with information in the article.

Test whether the average head acceleration is reduced by helmet wear at the .05 significance level.
b. The researchers were concerned that the mass of the helmet might increase the force experienced by the upper neck. The following summary information for resultant neck force (Newtons) is consistent with information in the article.

Test whether the average resultant neck force is increased by helmet wear at the .05 level.

c. If the null hypotheses in (a) and (b) are in fact both true, what can be said about the chance that at least one type I error is committed by the two tests?

Transcribed Image Text:

Helmet No helmet Sample size 24 24 Mean 43.1 75.4 SD 4.5 7.2