For Exercise 2.91, see page 106; for 2.92 and 2.93, see pages 106–107; for 2.94 to 2.96, see page 108; for 2.97 to 2.99, see page 109; and for 2.100 and 2.101, see pages 111–112.

Question 2.107

2.107 Condition on age

Refer to the previous exercise.

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  1. For each age group, compute the percent of students who are full-time and the percent of students who are part-time.
  2. Make a graphical display of the results that you found in part (a).
  3. If you have the appropriate software, make a mosaic plot.
  4. In a short paragraph, describe the relationship between age and full- or part-time status using your numerical and graphical summaries.
  5. Explain why you need only the percents of students who are full-time for your summary in part (b).
  6. Compare this way of summarizing the relationship between these two variables with what you presented in part (c) of the previous exercise.

2.107

(a) For Age 15 to 19: 89.7% are Full-time and 10.3% are Part-time. For Age 20 to 24: 81.82% are Full-time and 18.18% are Part-time. For Age 25 to 34: 50.06% are Full-time and 49.94% are Part-time. For Age 35 and Over: 27.15% are Full-time and 72.85% are Part-time. (d) Students aged 15–24 are much more likely to be Full-time, while students aged 35 and over and more likely to be Part-time. Students aged 25–34 are about equally likely to be Full- or Part-time students. (e) Because there are only 2 categories for Status, if we are given the percentage of Full-time students, the percentage of Part-time students must be 100% minus the percentage for Full-time. (f) Both are valid descriptions; it mostly depends on the condition in which you are interested. If we are interested in a particular age group, the current analysis likely has more meaning, whereas if we are interested in a particular status, the previous analysis has more meaning.