Saturday, May 15, 2010

Margin of Error and Confidence Level

I found the discussion of margin of error and confidence level in chapter 14 interesting. It makes a lot of sense to me because I am learning about it in my stats class and I can relate to the numbers and logic that Epstein discusses in the book. An example given in the book is about an opinion poll taken by voters that had a margin of error of 2% and a confidence level of 95%. Confidence interval means in this situation that there is a 95% chance of the poll that was to be taken the next day would turn out to be 53% with a plus minus of 2% in favor of the incumbent and 47% with a plus minus in favor of the challenger. Analyzing the data we can see that there is a good chance of this happening with the estimated range given of the percent of votes since there is a 95% confidence interval. If the confidence interval was replaced with 60% then this information would not be reliable because there is a 40% chance that the data collected would be wrong.

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