Refer to Example 12.7.2. Toschke et al. (A-17), who collected data on obesity status of children ages 5–6 years and the smoking status of the mother during the pregnancy, also reported on another outcome variable: whether the child was born premature (37 weeks or fewer of gestation). The following table summarizes the results of this aspect of the study. The same risk factor (smoking during pregnancy) is considered, but a case is now defined as a mother who gave birth prematurely.

Premature Birth Status Smoking Status During Pregnancy Cases Noncases Total Smoked throughout 36 370 406 Never smoked 168 3396 3564 Total 204 3766 3970 Source: A. M. Toschke, S. M. Montgomery, U. Pfeiffer, and R. von Kries, “Early Intrauterine Exposure to Tobacco-Inhaled Products and Obesity,” American Journal of Epidemiology, 158

(2003), 1068–1074.

Compute the odds ratio to determine if smoking throughout pregnancy is related to premature birth.

Use the chi-square test of independence to determine if one may conclude that there is an association between smoking throughout pregnancy and premature birth. Let a ¼ .05.