DO NOT POST THESE ANSWERS ONLINE© BFW Publishers 2014Chapter 11: Inference for Distributions of Categorical DataSection 11.2Check Your Understanding, page 699:1.For the main campus: 55/910 = 0.060 use Facebook several times a month or less, 215/910 =0.236 use it at least once a week, and 640/910 = 0.703use it at least once a day.For thecommonwealth campuses: 76/627 = 0.121 use it several times a month or less, 157/627 = 0.250use it at least once a week, and 394/627 = 0.628 use it at least once a day.2.It is important to compare proportions rather than counts because there was such a bigdifference in the sample size from the two different types of campuses.3.The biggest difference between the two types of campuses is that students on the maincampus are more likely to be everyday users of Facebook than students on the commonwealthcampuses.Also, those on the commonwealth campuses are more likely to use Facebook severaltimes a month or less than those students on the main campus.Check Your Understanding, page 705:1.0H: There is no difference in the distributions of Facebook use among students at the maincampus and students at the commonwealth campuses versusaH: There is a difference in thedistributions of Facebook use among students at the main campus and students at thecommonwealth campuses.2.First note that there are9106271537+=total students in the two samples,5576131+=totalstudents who use Facebook several times a month or less, 215 + 157 = 372 total students who useFacebook at least once a week, and 640 + 394 = 1034 total students who use Facebook at leastonce a day.The expected counts are in the table below.Use FacebookMain campusCommonwealth campusSeveral times a month()()13191077.561537=()()1316271537=53.44Once a week()()3729101537=220.25()()3726271537=151.75Once a day()()10349101537= 612.19()()10346271537= 421.81

DO NOT POST THESE ANSWERS ONLINE© BFW Publishers 2014The Practice of Statistics for 5/e3.()()()()()()22222225577.567653.44215220.25157151.7577.5653.44220.25151.75640612.19394421.8119.49612.19421.81χ−−−−=++++−−+=4.With df = (3 – 1)(2 – 1) = 2, theP-value is less than 0.0005. Using technology,P-value =2χcdf(lower: 19.49, upper: 1000, df: 2) = 0.000059.5. Assuming that there is no difference in the distributions of Facebook use between students onPenn State’s main campus and students at Penn State’s commonwealth campuses, there is a0.000059 probability of observing samples that show a difference in the distributions of Facebookuse among students at the main campus and the commonwealth campuses as large or larger thanthe one found in this study.6.Because theP-value of 0.000059 is less thanα= 0.05, we reject0H.There is convincingevidence that the distribution of Facebook use is different among students at Penn State’s maincampus and students at Penn State’s commonwealth campuses.Check Your Understanding, page 711:1.The bar graph shows the conditional distribution of quality of life for Canada and the U.S.2.State:We want to perform a test at theα= 0.01 level of0H: There is no difference in thedistribution of quality of life for patients who have suffered a heart attack in Canada and the U.S.

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Term

Winter

Professor

Rebecca Gattoni

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