XLSTAT: Calculate the Optimal Sample Size in Excel

 

Background

To ensure reliable results, a sample should represent the total population well. XLSTAT helps calculate the optimal sample size by considering the target population size, margin of error, and confidence level.

Dataset for Example

The attached telephone survey targets 5,000 people, but to reduce costs, we seek the optimal sample size ensuring a 95% confidence level and 2% margin of error.

 

Setting Up

• Open XLSTAT.

• Click on the Marketing/ Marketing tools menu and select the Sample size feature.

• The Sample Size dialog box appears. Enter 5000 for population size, 2% for margin of error, and 95% for confidence level.

• Click on the OK button to launch the computations.

• The results are displayed on a new Excel sheet.

 

Interpreting the Results

To achieve a 95% confidence level with a 2% margin of error, 1,623 surveys must be completed—about 32% of the total population. This is illustrated by the waffle chart showing the sample as a percentage of the population.