Hypothesis Tests

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• Hypothesis Tests
• for Proportions

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The Random Variable

• Recall
• Normal distribution
• Mean ? p
• Standard Deviation

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Hypothesis Testing for Proportions

• H0 p p0
• HA p gt p0
• Test is Reject H0 (Accept HA) if z gt z?
• The test statistic, z, is

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EXAMPLE

• Taste test between Coke and Pepsi
• 1000 cola drinkers tested
• 540 say they prefer Coke
• Can we conclude that more than 50 of cola
  drinkers favor Coke over Pepsi?
• Note

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The Hypothesis Test

• p true proportion of all cola drinkers who
  favor Coke
• H0 p .5
• HA p gt .5
• ? .05
• Reject H0 if z gt z.05 1.645

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Review

• The point estimate for p is
• The test statistic, z, is
• Use of Excel (COUNTA, COUNTIF Functions)