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# How to Calculate Margin of Error Between Polls

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• 1). Make a note of the population size for your poll, such as 500, which is expressed as "n."

• 2). Determine the confidence level for your poll or z-score. A confidence level of 95 will have a z-score of 1.96. This is also the standard deviation of 95 percent.

• 3). Convert the percentage of people you anticipate taking the poll to a decimal. If you expect at least 50 percent of the population to take the poll, the resulting decimal is 0.50. This is the sample size.

• 4). Subtract 0.50 from 1 for a result of 0.5. Multiply 0.50 by 0.50 for a result of 0.25, which is expressed as "v."

• 5). Calculate the square root of 0.25/500. Divide 0.25 by 500 on the calculator. Press the "Square Root" for a result of 0.00223606897.

• 6). Multiply 0.00223606897 by the standard deviation of 1.96 from Step 1 for a result of 0.0438. Move the decimal two spaces to the right and you will have a margin of error of 4.38 percent.

• 7). Repeat this process for another poll using a different population size and sample size.