Guide 77 · Attribution · GA4 + Tag Manager
The GA4 Model comparison report: read data-driven against last click before you change anything
Model comparison puts two attribution models side by side for one key event, so you can see which channels gain and lose credit before you touch the property setting.
After the trace, the report shows one table with a column per model, and the two columns add to the same purchase total while the channel rows differ.
Download the reference: the model comparison reference (JSON) (696 bytes, MD5 35bb50c8d1334e6c200753ea528eb47f). It holds the worked example from this guide with every figure recomputed. The file was built for this guide and checked the same day; it was not exported from a live property.
What you need
- An advertiser link on the property, or the report will not appear in Advertising.
- A key event with enough history to compare, such as purchase.
- A date range of at least 28 days, so the comparison is not one quiet week.
The trace
- Open Advertising on the left, then under Attribution click Model comparison. Google puts this report in the Advertising workspace, not in the standard Reports section.
- Pick the key event at the top. Use purchase if you sell online. The report compares models for that one event only, so changing the event changes every number in the table.
- Set the first model column to Data-driven and the second to Paid and organic last click. Those are the two models most properties choose between. First click, linear, time decay and position-based were removed in November 2023 and are not offered.
- Set the dimension to Default channel group. Each row is then a channel, and each channel has a conversion count under each model.
- Read the worked example in the download before reading your own table. For 240 purchases, data-driven gives Paid Search 48, Organic Search 96, Email 36 and Direct 60. Last click gives 72, 84, 24 and 60. Both columns add to 240. Paid Search loses 24 under data-driven, Organic Search gains 12, and Email gains 12.
- Decide from the difference, not from one column. If a channel gains under data-driven, it was helping earlier in the path and last click was hiding that help. Changing the property setting is a separate step in Admin, and this report does not change it.
Dead ends
DEAD END — THE REPORT IS MISSING. Attribution reports need an advertiser link, such as Google Ads. Without one, Advertising shows no attribution section. The fix is the link, not a setting inside the report.
DEAD END — COMPARING DIFFERENT EVENTS. The event picker sits at the top of the report. If two people compare different events, their tables disagree and neither is wrong.
DEAD END — READING THE REPORT AS A SETTING CHANGE. Model comparison only shows the numbers. The reporting model used by standard reports changes only in Admin, under Attribution settings.
End state
Both columns in the worked example add to 240 purchases. Paid Search falls by 24 under data-driven, Organic Search rises by 12, Email rises by 12, and Direct is unchanged at 60. The report shows the trade; it does not make it.
Sources
- Analytics Help — Get started with attribution — the three models in the Attribution reports, the November 2023 removal of the four rule-based models, and the Advertising path
Checked 11 November 2026. The click paths above are the ones in Google's help and developer pages, opened 11 November 2026. No step in this guide was run inside a live Analytics property or a live Tag Manager container, because both need a Google sign-in and this site does not sign in as anyone. The figures on this page were recomputed in Python 3 and are shown in the downloadable file, which was checked the same day. Google moves menu items without warning; if a path on this page no longer matches, the linked help page is the current map.