Is sexual activity among adolescent females related to whether one is a smoker or nonsmoker? Harriet Imrey, in an article appearing in The Journal of Irreproducible Results (Imrey, 1983), provided the following data from a sample of 508 girls between the ages of 14 and 17:
(a) Given this situation, state two equivalent expressions (in words) for the null hypothesis of independence in terms of proportions.
(b) State H1 (nondirectional) in words for each H0.
(c) Determine fo and fe for each of the four cells of this 2 × 2 contingency table. Present this information in a 2 × 2 table that includes row totals, column totals, and the grand total.
(d) Compute χ2 (using Formula [18.1]) and complete the test at α = 05.
(e) What is your general conclusion from this significant χ2 ?
(f) Translate each obtained frequency into a proportion based on its row frequency. What interpretation seems likely?