Module 1: Sampling and Data
Answers to Selected Exercises
Barbara Illowsky & OpenStax et al.
1. AIDS patients.
3. The average length of time (in months) AIDS patients live after treatment.
5. X = the length of time (in months) AIDS patients live after treatment
7.
- all children who take ski or snowboard lessons
- a group of these children
- the population mean age of children who take their first snowboard lesson
- the sample mean age of children who take their first snowboard lesson
- X = the age of one child who takes his or her first ski or snowboard lesson
- values for X, such as 3, 7, and so on
9.
- the clients of the insurance companies
- a group of the clients
- the mean health costs of the clients
- the mean health costs of the sample
- X = the health costs of one client
- values for X, such as 34, 9, 82, and so on
11.
- all the clients of this counselor
- a group of clients of this marriage counselor
- the proportion of all her clients who stay married
- the proportion of the sample of the counselor’s clients who stay married
- X = the number of couples who stay married
- yes, no
13.
- all people (maybe in a certain geographic area, such as the United States)
- a group of the people
- the proportion of all people who will buy the product
- the proportion of the sample who will buy the product
- X = the number of people who will buy it
- buy, not buy
15. a
17. b
19. a
21.
- 0.5242
- 0.03%
- 6.86%
- 823,088823,856
- quantitative discrete
- quantitative continuous
- In both years, underwater earthquakes produced massive tsunamis.
23. systematic
25. simple random
27. values for X, such as 3, 4, 11, and so on
29. No, we do not have enough information to make such a claim.
31. Take a simple random sample from each group. One way is by assigning a number to each patient and using a random number generator to randomly select patients.
33. This would be convenience sampling and is not random.
35. Yes, the sample size of 150 would be large enough to reflect a population of one school.
37. Even though the specific data support each researcher’s conclusions, the different results suggest that more data need to be collected before the researchers can reach a conclusion.
39. There is not enough information given to judge if either one is correct or incorrect.
41. The software program seems to work because the second study shows that more patients improve while using the software than not. Even though the difference is not as large as that in the first study, the results from the second study are likely more reliable and still show improvement.
43. Yes, because we cannot tell if the improvement was due to the software or the exercise; the data is confounded, and a reliable conclusion cannot be drawn. New studies should be performed.
45. No, even though the sample is large enough, the fact that the sample consists of volunteers makes it a self-selected sample, which is not reliable.
47. No, even though the sample is a large portion of the population, t