Sample Size - Proportion Estimation

Tutorial

When to use this tool

Use the Sample Size Calculator to obtain the sample size required to estimate a population proportion with a specified confidence level and precision (margin of error). The calculator displays the sample size required to estimate the true value of the proportion with the desired precision and confidence for a large or infinite population.

How to use this tool in EngineRoom

To use the Sample Size Calculator, select the Measure menu > Sample Size Calculator... > Sample Size Calculator - Proportion Estimation. The study opens on the workspace:

Example:

Find the sample size required to estimate the population proportion given the following information:

• Historical value for the proportion = 0.8
• Desired margin of error = +/- 0.05
• Desired significance level (= 1 - desired confidence level) = 1 - 0.95 = 0.05

Steps:

1. Open the Sample Size Calculator - Proportion Estimation tool onto the workspace.
2. Enter the historical proportion value as 0.8.
3. Click "Continue."
4. Enter the desired margin of error as 0.05.
5. Click "Continue."
6. Enter the significance level (alpha) as 0.05.
7. Click "Continue."
8. The study displays the sample size required to estimate the population proportion for the given inputs. In this example, it is 246.

Instructor Resources

PowerPoint Download