Calculating geometric mean and confidence intervals for time-on-task data

This page was referenced in the November, 2006 Interactions magazine at the end of the article: "Making the Fuzzy Parts of ROI Clear" by John Sorflaten.

As mentioned in the article, you can calculate the geometric mean and confidence intervals using Jeff Sauro's calculator. (See example of Jeff's analysis in graphic below.)

Additionally, you can use your spreadsheet to make these calculations. For instructions on this procedure and creating charts showing the "Y-error bars" (margins of error), download this Excel spreadsheet.