Tableau + GA4 Gotchas: Analyzing region, city and First User Source Medium data

Return on Development

I found something interesting while using the Google Analytics 4 integration in Tableau.

I’m trying to pull data from Tableau using these dimensions:

  • Region
  • Date
  • First User Source Medium

With this metric:

  • Sessions

I noticed that when I leave off Region, I have a fewer “First User Source Medium:”

When I add Region:

What’s going on here?

Adding Region seems to duplicate some of the First User Source Mediums. If I switch to Count Distinct on First User Source Mediums, the numbers match:

But then, add City and we see a reduction:

© 2025 Return on Development, Seth Hayward