Chapter 6.3（课件）- 《统计学基础（英文版）》同步教学（人民大学版）

Chapter Confidence Intervals 1 Copyright 2019, 2015, 2012, Pearson Education, Inc. 1 Larson/Farber 6th ed Chapter 1 Chapter Outline 6.1 Confidence Intervals for the Mean ( Known) 6.2 Confidence Intervals for the Mean ( Unknown) 6.3 Confidence Intervals for Population Proportions 6.4 Confidence Intervals for Variance and Standard Deviation . 1 Copyright 2019, 2015, 2012, Pearson Education, Inc. Section 6.3 Confidence Intervals for Population Proportions . 1 Copyright 2019, 2015, 2012, Pearson Education, Inc. Section 6.3 Objectives How to find a point estimate for the population proportion How to construct and interpret confidence intervals for a population proportion How to determine the minimum sample size required when estimating a population proportion . 1 Copyright 2019, 2015, 2012, Pearson Education, Inc. Population Proportion Population Proportion, p The probability of success in a single trial of a binomial experiment is p . 1 Copyright 2019, 2015, 2012, Pearson Education, Inc. 5 The point estimate for p, the population proportion of successes, is given by the proportion of successes in a sample and is denoted by = Sample proportion where x is the number of successes in the sample and n is the sample size. The point estimate for the population proportion of failures is = 1 – . The symbols and are read as “p hat” and “q hat.” Point Estimate for p . 1 Copyright 2019, 2015, 2012, Pearson Education, Inc. 6 Example: Point Estimate for p In a survey of 1550 U.S. adults, 1054 said that they use the social media website Facebook. Find a point estimate for the population proportion of U.S. adults who use Facebook. (Adapted from Pew Research Center) Solution: The number of successes is the number of adults who use Facebook, so x = 1054. The sample size is n = 1550. So, the sample proportion is = = = 0.68 = 68% . 1 Copyright 2019, 2015, 2012, Pearson Education, Inc. Confidence Intervals for a Population Proportion A c-confidence interval for the