> ## Documentation Index
> Fetch the complete documentation index at: https://docs.invoca.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Why Does Invoca Data Change After Being Sent to Google Analytics?

> UTM traffic variables are deduced from the session ID or Client ID Invoca sends, stitching back to what the Google Analytics tag captured for that session.

**Applies to:** Invoca numbers with Marketing Data fields applied

## Symptoms

Invoca Marketing Data field values are sent to Google Analytics with particular values, but those values change after reaching Google Analytics.

## Resolution

UTM traffic variables aren't passed as literal values — they're deduced based on the session ID or Client ID Invoca sends, which Google Analytics stitches back to whatever its own tag captured for that session on the website. Some difference between the Invoca-reported value and what appears in Google Analytics is expected as a result.

## Where to go next

* [Google Analytics 4.0 (GA4): FAQs](/s/article/ga4-faqs)
* [Google Analytics 4.0 (GA4): Installation Guide](/s/article/ga4-installation-guide)