| Stat 251: Statistical Methods I | Last updated 09/19/2008 |
Complete the following exercises from your text: pages 79-83, #1, 10, 11
There is a typo in #11 -- the correct word is Capitalized below.
1) Consider all of the books in a bookstore as the observational units in a study.
(a) Identify three quantitative variables that could be recorded on these books. (Be sure to state them appropriately.)
(b) Identify three categorical variables that could be recorded on these books. (Be sure to state them appropriately.)
10) The following tables display the status of the passengers of the Titanic, their gender, and whether they were a child or an adult, as determined by Dawson (1995). (The historical sources didn’t completely agree with each other.)
Child
|
|
Male |
Female |
|
Survived |
29 |
28 |
|
Died |
35 |
17 |
Adult
|
|
Male |
Female |
|
Survived |
338 |
316 |
|
Died |
1329 |
109 |
(a) What was the odds ratio of survival for a child compared to an adult?
(b) What was the odds ratio of survival for a female compared to a male?
(c) Was the association between survival status and gender stronger for the children or for the adults? Justify your conclusion.
(d) Is it reasonable to conclude that adult females were about 11 times more likely to survive than adult males? Explain.
(e) Fill in the cells of the following (hypothetical) table so that the gender and survival status variables are independent:
|
|
Male |
Female |
Total |
|
Survived |
|
|
58 |
|
Died |
|
|
51 |
|
Total |
64 |
45 |
109 |
(f) Calculate the odds ratio for the table that you created in (e). Does its value make sense? Explain.
11) In 1846, the Donner and Reed families left Springfield< Illinois, for California. In July, they reached Fort Bridger, Wyoming. The leaders decided to attempt a new and untested route to the Sacramento Valley, where they were delayed by difficult river and desert crossings. The group became stranded in the eastern Sierra Nevada mountains when the region was hit by heavy snows in late October. By the time the last survivor was rescued on April 21, 1847, 40 of the 87 members had died from famine and exposure to extreme cold. Among the adults (15 years and older), 5 of the 15 females DIED, and 20 of the 30 males died.
(a) Create a two-way table and segmented bar graph to summarize the gender differences in survival for the Donner Party.
(b) Were females more likely to survive than males? Justify your answer.
(c) Would it be reasonable to use these results as proof than females were more apt to survive than males based solely on their gender? Explain.