Statistics:Confidence Intervals and Errors

1happyday said:

Confidence Intervals and Errors: An opinion poll asks 1500 randomly chosen United States residents their opinions about relations with the nations of Europe. The announced margin of error for 95% confidence is + 3 points. But some people were not on the list from which respondents were chosen, some could not be contacted, and some refused to answer. Does the announced margin of error include errors from these causes? Explain your answer.

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