Understanding Business Statistics

CHAPTER 8

Interval Estimates for Proportions, Mean Differences and Proportion Differences

LEARNING OBJECTIVES

After completing the chapter, you should be able to

1. Build and interpret a confidence interval estimate of a population proportion using the appropriate sampling distribution.
2. Build and interpret a confidence interval estimate of the difference between two population means using the appropriate sampling distribution.
3. Build and interpret a confidence interval estimate of the difference between two population proportions using the appropriate sampling distribution.
4. Build and interpret a confidence interval estimate of the difference between two population means using matched samples.

EVERYDAY STATISTICS

Survey says…

The 1948 election of Harry Truman stands as one of the most dramatic upsets in American political history. Political pollsters, pundits and the press got it completely wrong. In fact, pollsters were so sure that Thomas Dewey, the Republican candidate, would trounce Truman in the general election that some of them stopped sampling voter opinion nearly a month before Election Day. Said Elmo Roper, founder of the prominent Roper Poll, “My whole inclination is to predict the election of Thomas E. Dewey by a heavy margin and devote my time and efforts to other things.” At that point Truman trailed Dewey by an average of 10 percentage points in the polls. One month ...