Be careful when averaging percentages

Posted on:  01/12/2019
Be careful when averaging percentages

Caution should be used when averaging percentages. As an example, we asked 500 kids and 4500 adults if they like Trix cereal. The kids, 98%, liked Trix cereal. The adults, 42%. Add 98% and 42% and you get 140%. Divide by 2 and that is 70%. (98+42=140 / 2 = 70). The issue is you didn’t ask the same number of kids as you did adults. This is when a weighted average is needed.
An Excel PivotTable has a feature called calculated field. I’ll use it to get the weighted average.

YouTube video on Averaging Percentages

Steps to create a calculated field in a PivotTable

  1. Click inside the PivotTable.
  2. Click on the Analyze tab, in the Calculations group, click Fields, Items, & Sets, and then click Calculated Field.
  3. In the Name box, type a name for the field.
  4. In the Formula box, enter the formula for the field.
  5. Click Add.