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Introduction to Confidence Intervals :: More Margin of Error

Now, If you've ever heard the news say a race is too close to call or there's a "statistical tie" it's because the width of both confidence intervals are overlapping enough that there's no clear leader. What does that mean? Imagine that a lot fewer people were surveyed for the poll taken by the Star-Tribune Newspaper and the margin of error was now +/- 6%. This new relationship is displayed in the figure below.

Notice how part of the confidence intervals overlap? The +/- 6% Margin of Error on the top of John Daniel's 45 % overlaps with the - 6% of Jim Bean's 55%. This means that if the poll were to be taken again, there's a reasonable chance that John Daniels might be leading over Jim Bean in the polls. How great of a chance is there? To know that you need to understand the confidence level.

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