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Chapter 7: Q. T7.2 (page 486)

The Gallup Poll has decided to increase the size of its random sample of voters from about 1500 people to about 4000 people right before an election. The poll is designed to estimate the proportion of voters who favor a new law banning smoking in public buildings. The effect of this increase is to

a. reduce the bias of the estimate.

b. increase the bias of the estimate.

c. reduce the variability of the estimate.

d. increase the variability of the estimate.

e. reduce the bias and variability of the estimate.

Short Answer

Expert verified

(c) The effect of this increase is to reduce the variability of the estimate.

Step by step solution

01

Given Information

Right before an election, the Gallup Poll decided to raise the size of its random sample of voters from 1500 to 4000 persons. The purpose of the poll is to determine the percentage of voters who support a new law prohibiting smoking in public places.

02

Explanation for correct option

Because the inaccuracies are produced by the sampling techniques, sample size has no bearing on them. When the sample size is increased, the variability is reduced since a larger sample provides more information about the population and thus better estimates.

As a result, the best solution is (c)

03

Explanation for incorrect option

a. reduce the bias of the estimate is not the answer.

b. increase the bias of the estimate is not the answer.

d. increase the variability of the estimate is not the answer.

e. reduce the bias and variability of the estimate is not the answer.

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Most popular questions from this chapter

The distribution of scores on the mathematics part of the SAT exam in a recent year was approximately Normal with mean 515 and standard deviation 114 . Imagine choosing many SRSs of 100 students who took the exam and averaging their SAT Math scores. Which of the following are the mean and standard deviation of the sampling distribution of x-?x¯?

a. Mean =515,SD=114

b. Mean =515,SD=114/100SD=114/100

c. Mean role="math" localid="1654342976765" =515/100,SD=114/100

d. Mean role="math" localid="1654343050312" =515/100,SD=114/100SD=114/10

e. Cannot be determined without knowing the 100 scores.

A 10-question multiple-choice exam offers 5 choices for each question. Jason just guesses the answers, so he has probability 15of getting any one answer correct. You want to perform a simulation to determine the number of correct answers that Jason gets. What would be a proper way to use a table of random digits to do this?

a. One digit from the random digit table simulates one answer, with 5 = correct and all other digits = incorrect. Ten digits from the table simulate 10 answers.

b. One digit from the random digit table simulates one answer, with 0 or 1 = correct and all other digits = incorrect. Ten digits from the table simulate 10 answers.

c. One digit from the random digit table simulates one answer, with odd = correct and even = incorrect. Ten digits from the table simulate 10 answers.

d. One digit from the random digit table simulates one answer, with 0 or 1 = correct and all other digits = incorrect, ignoring repeats. Ten digits from the table simulate 10 answers.

e. Two digits from the random digit table simulate one answer, with 00 to 20 = correct and 21 to 99 = incorrect. Ten pairs of digits from the table simulate 10 answers.

Refer to the small population of 5students in the table.

Sample means List all 10 possible SRSs of size n=2, calculate the

mean quiz score for each sample, and display the sampling distribution of the sample

mean on a dotplot.

Unemployment Each month, the Current Population Survey interviews about 60,000 randomly selected U.S. adults. One of their goals is to estimate the national unemployment rate. In October 2016,4.9% of those interviewed were unemployed.

Social scientists are interested in the association between high school graduation rate (HSGR, measured as a percent) and the percent of U.S. families living in poverty (POV). Data were collected from all 50 states and the District of Columbia, and a regression analysis was conducted.

The resulting least-squares regression line is given by POV∧=59.2-0.620(HSGR) POV^=59.2-0.620(HSGR) with r2=0.802r2=0.802. Based on the information, which of the following is the best interpretation for the slope of the least-squares regression line?

a. For each 1% increase in the graduation rate, the percent of families living in poverty is predicted to decrease by approximately 0.896 .

b. For each 1 % increase in the graduation rate, the percent of families living in poverty is predicted to decrease by approximately 0.802.

c. For each 1 % increase in the graduation rate, the percent of families living in poverty is predicted to decrease by approximately 0.620.

d. For each 1 % increase in the percent of families living in poverty, the graduation rate is predicted to decrease by approximately 0.802.

e. For each 1 % increase in the percent of families living in poverty, the graduation rate is predicted to decrease by approximately 0.620.
See all solutions

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