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Chapter 1: Q. 89 (page 5)
No replacement To use a binomial distribution to approximate the count of successes in an SRS, why do we require that the sample size be no more than of the population size?
The probability of success will change, particularly after each drawn element.
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Use the following information to answer the next seven exercises: Studies are often done by pharmaceutical companies to determine the effectiveness of a treatment program. Suppose that a new AIDS antibody drug is currently under study. It is given to patients once the AIDS symptoms have revealed themselves. Of interest is the average (mean) length of time in months patients live once starting the treatment. Two researchers each follow a different set of 40 AIDS patients from the start of treatment until their deaths. The following data (in months) are collected.
Researcher A: 3; 4; 11; 15; 16; 17; 22; 44; 37; 16; 14; 24; 25; 15; 26; 27; 33; 29; 35; 44; 13; 21; 22; 10; 12; 8; 40; 32; 26; 27; 31; 34; 29; 17; 8; 24; 18; 47; 33; 34
Researcher B: 3; 14; 11; 5; 16; 17; 28; 41; 31; 18; 14; 14; 26; 25; 21; 22; 31; 2; 35; 44; 23; 21; 21; 16; 12; 18; 41; 22; 16; 25; 33; 34; 29; 13; 18; 24; 23; 42; 33; 29
Complete the tables using the data provided:
For the following four exercises, determine the type of sampling used (simple random, stratified, systematic, cluster, or convenience).
A computer generates 100 random numbers, and 100 people whose names correspond with the numbers on the list are chosen.
List some practical difficulties involved in getting accurate results from a telephone survey.
A scholarly article about response rates begins with the following quote:
鈥淒eclining contact and cooperation rates in random digit dial (RDD) national telephone surveys raise serious concerns about the validity of estimates drawn from such research.鈥�The Pew Research Center for People and the Press admits: 鈥淭he percentage of people we interview 鈥� out of all we try to interview 鈥� has been declining over the past decade or more.鈥�
a. What are some reasons for the decline in response rate over the past decade?
b. Explain why researchers are concerned with the impact of the declining response rate on public opinion polls.
Fifty part-time students were asked how many courses they were taking this term. The (incomplete) results are shown below:
a. Fill in the blanks in Table .
b. What percent of students take exactly two courses?
c. What percent of students take one or two courses?
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