A sociologist wants to discover whether the sexual activity of females between the ages of 15 and 19 years and family structure are associated. She randomly selects 380 females between the ages of 15 and 19 years and asks each to disclose her family structure at age 14 and whether she has had sexual intercourse. The results are shown in the table. Data are based on information obtained from the National Center for Health Statistics.

(a) Compute the expected values of each cell under the assumption of independence.
(b) Verify that the requirements for performing a chi-square test of independence are satisfied.
(c) Compute the chi-square test statistic.
(d) Test whether family structure and sexual activity of 15- to 19-year-old females are independent at the a = 0.05 level of significance.
(e) Compare the observed frequencies with the expected frequencies. Which cell contributed most to the test statistic? Was the expected frequency greater than or less than the observed frequency? What does this information tell you?
(f) Construct a conditional distribution by family structure and draw a bar graph. Does this evidence support your conclusion in part (d)?

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Family Structure Both Biological Had Sexual or Adoptive Intercourse Parents Parent and Nonparental Single Parent Stepparent Guardian Yes 64 59 44 32 No 86 41 36 18