1. Independent Samples: Comparing Proportions
Lecture 42
Section 11.5
Fri, Apr 8, 2005

2. Confidence Intervals A confidence interval for p1 – p2 is of the form

3. Confidence Intervals
Since we are trying to estimate the difference between p1 and p2, it would not make sense to use the pooled estimate of.

4. Example
Re-do Example 11.8, p. 669, as a confidence interval problem.

5. Confidence Intervals on the TI-83
Press STAT.
Select 2-PropZInt.
A window appears.
Enter x1.
Enter n1.
Enter x2.
Enter n2.

6. Confidence Intervals on the TI-83
Enter the confidence level.
Select Calculate.
Press ENTER.

7. Confidence Intervals on the TI-83
A window appears with the following information.
The confidence interval for p1 – p2.
The value of p1^.
The value of p2^.
n1.
n2.

8. Example
Re-do Example 11.8, p. 669, using the TI-83.

9. Let’s Do It!
Let’s do it! 11.7, p. 671 – HMOs on the Rise.