Chapter 22 and 23

# Chapter 22 and 23 - Chapter 22 Comparing Two Proportions...

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Chapter 22 Comparing Two Proportions

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Chapter 22 Comparing Two Proportions Assumptions: 1. Randomization/Independence Condition: Data should be drawn independently and at random 2. 10% Condition: If the data are sampled without replacement, the sample should not exceed 10% of the population 3. Success/Failure Condition: Both groups should be big enough to have at least 10 successes and 10 failures
Example Researchers contacted more than 25000 Americans aged 24 or above to find if they have graduated from high school: From 12460 males: 84.9% graduated From 12678 females: 88.1% graduated Create a 90% confidence interval for the difference in graduation rate between males and females. Check the assumptions

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Solution P_{1}^-P_{2}^=-0.032 SE = .00322 Z* = 1.645 Conf. Interval: (-.039, -.0249)
Chapter 22 Comparing Two Proportions

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Example Retirement: The Employee Benefit Research Institute reports that 27% of males anticipate having enough money to live comfortable in retirement, but only 18% of females express that confidence. If these results were based on samples of 250 people of each gender, would you consider this strong evidence that men and women have different outlooks?
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## This note was uploaded on 03/27/2012 for the course STT 200 taught by Professor Dikong during the Spring '08 term at Michigan State University.

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Chapter 22 and 23 - Chapter 22 Comparing Two Proportions...

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