D.14 Answers: Numerical summaries for qualitative data

Answers to exercises in Sect. 14.9.

Answer to Exercise 14.1: 1. Vomited: 0.50 had beer then wine; 0.50 had wine only.
Didn’t vomit: 0.738 had beer then wine, 0.262 had wine only. They tell us the proportion that drank various things, among those who did and didn’t vomit. 2. Beer then wine: 8.8% vomited and 91.2% didn’t; Wine only: 21.4% vomited and 78.6% didn’t. They tell us the percentage that vomited, for each drinking type. 3. (6+6)/(6+6+62+22)=0.125. 4. 6/22=0.2727. 5. 6/62=0.096774. 6. 0.27272/0.096774=2.82. 7. 0.096774/0.27272=0.354.
Answer to Exercise 14.2: 1. 91/(91+188)=0.32616. 2. 188/91=2.0659, or about 2.07. 3. 22/13=1.6923, or about 1.69. 4. 13/(13+22)=0.37142, or about 37.1%. 5. 2.0659/1.6923=1.22.
Answer to Exercise 14.3: 1. 21/114, or about 18.4%. 2. 14/54, or about 25.9%. 3. 7/60, or about 11.7%. 4. 21/93, or about 0.226. 5. 14/40, or 0.35. 6. 7/53, or about 0.132. 7. 0.35/0.132, or about 2.7. 8. The odds of no August rainfall in Emerald is 2.7 times higher in months with non-positive SOI.
Answer to Exercise 14.4: 1. 45.9%. 2. 61.4%. 3. 0.848. 4. 1.59. 5. 1.15. 6. 0.533. 7. The odds of reporting back pain from carrying school bags, comparing boys to girls.