Bicycle Helmets A study was conducted of 531 persons injured in bicycle crashes, and randomly selected sample results are summarized in the accompanying table (based on results from “A Case-Control Study of the Effectiveness of Bicycle Safety Helmets in Preventing Facial Injury,” by Thompson et al., American Journal of Public Health, Vol. 80, No. 12). The XLSTAT results also are shown. At the 0.05 significance level, test the claim that wearing a helmet has no effect on whether facial injuries are received. Based on these results, does a helmet seem to be effective in helping to prevent facial injuries in a crash?

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Chi-square (Observed value) Chi-square (Critical value) 10.708 Helmet Worn No Helmet Facial Injuries Received All Injuries Nonfacial 30 182 DF 83 236 p-value alpha 3.841 1 0.001 0.05