A Gallup Poll in December 2000 asked “Do you think this country would be governed better or governed worse if more women were in political office?” Of the 1026 adults in the sample, 57% said “better.” Gallup added “For results based on the total sample of National Adults, one can say with 95% confidence that the margin of sampling error is ± 3 percentage points.” Explain to someone who knows no statistics what the phrase “95% confidence” means here.

Answer: That means that with probability 0.95, the interval 57% ± 3% will contain the real population proportion. In other words, in approximately 95 out of each 100 times, the sample proportion ± 3% will contain the real population proportion.

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