Using embedded queries with dynamic segments, the report shows how many of your new website visitors returned to your site over each of the past 7 days.
Use the report as-is to gauge short term campaign effectiveness, or use the technique in your own custom analysis.
Requires: Analytics Edge Core Add-in (free license) with Google Analytics connector
Download the workbook: GoogleAnalytics-7DayCohortAnalysis-2-0.xlsx
A companion Help article shows how to make a 12-Month Cohort Analysis and includes a sample report.