Oprah Winfrey endorsed Barack Obama in the Democratic presidential primary. Does Oprah's endorsement make a difference? If so, we would expect support for Obama to be higher among people who watch Oprah regularly than among people who don't. The table below gives data on watching Oprah and support for Barack Obama among a random sample of the U.S. population.
a) Is there any evidence that Oprah's endorsement makes a difference (answer this part without conducting a hypothesis test)? Justify your answer by computing appropriate statistics.
b) If there does appear to be an association between watching Oprah and supporting Obama, is this association statistically significant at the .05 level? Show all work.
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Supports Obama?
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Yes
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No
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Watches Oprah?
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Yes
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150
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120
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No
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200
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230
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