1 / 16

Chapter 18 Inference about a Population Proportion

Chapter 18 Inference about a Population Proportion. Outline. The sample proportion The sampling distribution of Conditions for inference Large-sample confidence intervals for a population proportion Choosing the sample size Significance tests for a proportion. “ p-hat”.

mccaina
Télécharger la présentation

Chapter 18 Inference about a Population Proportion

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 18Inference about a Population Proportion

  2. Outline • The sample proportion • The sampling distribution of • Conditions for inference • Large-sample confidence intervals for a population proportion • Choosing the sample size • Significance tests for a proportion

  3. “p-hat” 1. The Sample proportion • The proportion of a population that has some outcome (“success”) is p. • The proportion of successes in a sample is measured by the sample proportion:

  4. 2. The sampling distribution of

  5. 3. Conditions for inference

  6. Standard Error of Since the population proportion p is unknown, the standard deviation of the sample proportion will need to be estimated by substituting for p.

  7. 4. Large-sample confidence intervals for a population proportion

  8. Examples • Example 18.4 Estimating risky behavior (Page 476) • Example 18.5 Are the conditions met? (Page 476) • Exercise 18.8 No confidence interval. (Page 477)

  9. 5. Accurate C.I. for a proportion • Example 18.6 (P479) Shaq’s free shows

  10. 6. Choosing the sample size • The margin of error in our confidence interval is • We may like to choose the sample size n to achieve a certain margin of error.

  11. The sample size

  12. Guess the sample proportion: • Since we don’t know prior to sampling, we will have to use a guess p* for . There are two ways to do this: • Use a guess p* based on a pilot study or on past experience. • Use p*=0.50 as the guess. This guess is conservative, as it gives a margin of error bigger than the true margin of error. (Conservative)

  13. Example • Example 18.7 Planning a poll (Page 482)

  14. 7. Significance tests for a proportion

  15. Examples • Example 18.8 Is this coin fair? (Page 484) • Example 18.9 Estimating the chance of head (Page 485)

More Related