Inference for Population Proportions

1
Inference for Population Proportions
2
Estimate a single population proportion

• What proportion of Americans age 18 and over
  favor Barack Obama over Hillary Clinton?

3
Compare two population proportions

• Does the passing rate of college courses differ
  between students who engage in extra-curricular
  activities and those who do not?

4
Conditions for Inference About a Proportion

• The data are from an SRS
• The population is at least 10 times as large as
  the sample (Independence)
• np gt 10 and n(1 p) gt 10 (Normal)

5
z-procedures

• Normal approximation to the Binomial
• z-procedures are associated with Normal
  distributions

6
Confidence Interval for One Proportion

• 1-Prop Z Interval

7
Significance Tests for One Proportion

• 1-Prop Z Test

8
Confidence Interval for Comparing Two Proportions

• 2 Prop Z Interval

9
Significance for Comparing Two Proportions

• 2 Prop Z Interval

10
Practice!

• TB p. 719 12.35 Ricardo, Alyssa, Alex C.,
  Jennifer, James
• TB p. 720 12.37 a, c Cris, Travis, Daisy, Alex
  S.
• TB p. 721 12.41 Sam, Emily, Peter, Anthony
• TB p. 721 12.44 Mike, Davina, Darius, Natasha,
  Erica