For example: 1000 voters were surveyed and 39±2% of the voters agreeing with the president. In this example N=1000 and the margin of error (MoE) is 2%. What isn't given is the confidence interval. Is it 90%, 95%, or 99%? Does it matter? A confidence interval of 95% is most commonly used when reporting survey results.
Visit the website http://www.pollingreport.com.
This website lists several public opinion polls. Search the site and find a poll where the sample size and margin of error are given. Try to find a poll dealing with topic in your profession. Give the topic of the poll, the sample size and margin of error. Do you think the results from the sample reflect public opinion?
When the results of a survey or poll are published, the sample size and the margin of error are both given.?
That's because the confidence level in polling uses 95% confidence as the standard. You are correct that varying the confidence level would widen or narrow the margin of error interval, but public polling results use the same confidence level.
For one example done by Gallup, see:
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