91影视

Why men and women play sports Do men and women participate in sports for the same reasons? One goal for sports participants is social comparision鈥攖he desire to win or to do better than other people. Another is mastery鈥攖he desire to improve one鈥檚 skills or to try one鈥檚 best. A study on why students participate in sports collected data from independent random samples of 67 male and 67 female under-graduates at a large university 15 Each student was classified into one of four categories based on his or her responses to a questionnaire about sports goals. The four categories were high social comparison鈥� high mastery (HSC-HM), high social comparison鈥� low mastery (HSC-LM), low social comparison鈥揾igh mastery (LSC-HM), and low social comparison鈥搇ow mastery (LSC-LM). One purpose of the study was to compare the goals of male and female students. Here are the data displayed in a two-way table: Observed Counts for Sports Goals

(a) Check that the conditions for performing the chi-square test are met.

(b) Use Table C to find the P-value. Then use your calculator鈥檚 C2cdf command.

(c) Interpret the P-value from the calculator in context.

(d) What conclusion would you draw? Justify your answer.

32. How are schools doing? Refer to Exercises 28 and 30 .

(a) Check that the conditions for performing the chi-square test are met.

(b) Use Table $\mathrm{C}$to find the $P$-value. Then use your calculator's ${蠂}^2\mathrm{cdf}$command.

(c) Interpret the $P$-value from the calculator in context.

(d) What conclusion would you draw? Justify your answer.

How is the hatching of water python eggs influenced by the temperature of the snake鈥檚 nest? Researchers randomly assigned newly laid eggs to one of three water temperatures: hot, neutral, or cold. Hot duplicates the extra warmth provided by the mother python, and cold duplicates the absence of the mother. Here are the data on the number of eggs and the number that hatched

(a) Make a two-way table of temperature by outcome (hatched or not). Calculate the proportion of eggs in each group that hatched. The researchers believed that eggs would not hatch in cold water. Do the data support that belief?

(b) Are the differences between the three groups statistically significant? Give appropriate evidence to support your answer

How do U.S. residents who travel overseas for leisure differ from those who travel for business? The following is the breakdown by occupation:

Explain why we can鈥檛 use a chi-square test to learn whether these two distributions differ significantly.

How to quit smoking It鈥檚 hard for smokers to quit. Perhaps prescribing a drug to fight depression will work as well as the usual nicotine patch. Perhaps combining the patch and the drug will work better than either treatment alone. Here are data from a randomized, double-blind trial that compared four treatments. A 鈥渟uccess鈥� means that the subject did not smoke for a year following the beginning of the study.

Group Treatment Subjects Successes

1 Nicotine patch 244 40

2 Drug 244 74

3 Patch plus drug 245 87

4 Placebo 160 25

(a) Summarize these data in a two-way table.

(b) Make a graph to compare the success rates for the four treatments. Describe what you see.

(c) Explain in words what the null hypothesis H0: p1 = p2 = p3 = p4 says about subjects鈥� smoking habits.

(d) Find the expected counts if H0 is true, and display them in a two-way table similar to the table of observed counts.

Aspirin prevents blood from clotting and so helps prevent strokes. The Second European Stroke Prevention Study asked whether adding another anticlotting drug named dipyridamole would be more effective for patients who had already had a stroke. Here are the data on strokes during the two years of the study:

(a) Summarize these data in a two-way table.

(b) Make a graph to compare the rates of strokes for the four treatments. Describe what you see.

(c) Explain in words what the null hypothesis $H_0$: p1 = p2 = p3 = p4 says about the incidence of strokes.

(d) Find the expected counts if H0 is true, and display them in a two-way table similar to the table of observed counts

Refer to Exercise 37. Do the data provide convincing evidence of a difference in the effectiveness of the four treatments? Carry out an appropriate test at the $伪=0.05$significance level

Roulette Calculate the chi-square statistic for the data in Exercise $2$. Show your work.

Assuming $H_0$is true, the expected number of Hispanic drivers who would receive a ticket is

(a) 8

(c) 11.

(e) 12.

(b) 10.36

(d) 11.84

Do the data provide convincing evidence of a difference in the effectiveness of the four treatments? Carry out an appropriate test at the $伪=0.05$significance level.