Table 8.24 cross-classifies 68,694 passengers in autos and light trucks involved in accidents in the state of Maine by whether they were wearing a seat belt and by whether they were injured or killed. Describe the association using

(a) The difference between two proportions, treating whether injured or killed as the response variable.

(b) The odds ratio.

TABLE 8.24 Injury Yes No Seat Yes 2409 35,383 Belt No 3865 27,037 Source: Thanks to Dr. Cristanna Cook, Medical Care Development, Augusta, Maine, for supplying these data.