In an election poll, 200 people were surveyed and 45% expressed their likelihood to vote for a particular candidate. the margin of error on this estimated support is closest to

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Wagner

5 December, 08:53

In an election poll, 200 people were surveyed and 45% expressed their likelihood to vote for a particular candidate. the margin of error on this estimated support is closest to

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William Newman · Answer 1

A margin of error is an amount (usually small) that is allowed for in case of miscalculation or change of circumstances. A general approach for finding a margin of error involves using the standard deviation of a sample proportion.

Roughly 95% of all normally distributed data fall within two standard deviations of the mean. So the margin of error is two times the standard deviation (SD)

margin of error = 2*SD

SD=sqrt (p * (1-p) / n)

p is probability of the event and n is the sample size.

In our case, p=0.45 and n=200.

SD=sqrt (0.45*0.55/200) = sqrt (0.001) - 0.03