THE SHORT ANSWER
Marketing attribution applies a rule or model to assign conversion credit to observed interactions. First-click, last-click, position-based and data-driven approaches embody different assumptions; platforms and analytics systems may report different valid views because they observe and model different evidence.
Each model answers a constructed question
| Model | Credit rule | What it emphasizes |
|---|---|---|
| First click | All credit to the first eligible touchpoint | Introduction |
| Last click | All credit to the final eligible non-direct touchpoint | Closure |
| Position based | More credit to selected positions | Introduction and closure |
| Data driven | Algorithmic fractional credit from available path data | Estimated contribution within the model |
First-click and position-based models remain useful concepts for understanding assumptions, but Google Analytics removed first click, linear, time-decay and position-based options from its current Attribution reports in November 2023. Current product choices should be checked in official documentation.
Evidence & context: Google Analytics Help · Google Analytics Help
Why Google Ads, Meta, GA4 and CRM can disagree
| System | Typical scope |
|---|---|
| Ad platform | Interactions it observes under its attribution settings |
| Analytics | Tagged site or app journeys under its identity and channel rules |
| CRM | Known leads, opportunities and customers under operational rules |
| Finance or order system | Completed and reconciled commercial outcomes |
View-through eligibility, identity, time windows, conversion date, processing, consent, modeling, duplicates and cancellation treatment can all change the total. Reconcile definitions before treating a discrepancy as an error.
Evidence & context: Google Analytics Help · Google Analytics Help
Assisted paths add context, not certainty
Path reports can show channels appearing early, in the middle or late before a selected key event. That evidence can reveal recurring roles and time to conversion. It includes only observed eligible touchpoints and journeys that reach the chosen event.
A long path does not prove every touchpoint was necessary. A short path does not prove earlier unobserved influence was absent.
Evidence & context: Google Analytics Help
Use attribution for reporting and optimization
Choose a primary cross-channel view, preserve platform reports for delivery optimization and reconcile both to business outcomes. Document the model, window, scope and date of any setting change.
The Performance Marketing resource What Attribution Can and Cannot Tell You applies these limits to campaign decisions. Continue here to incrementality when the question is what marketing caused.
Sources & further reading
- Get started with attribution
Google Analytics Help. Official definitions of current GA4 attribution settings and models. Product options can change, and assigned credit is not the same as incremental impact.
- Key events attribution paths report
Google Analytics Help. Official documentation for observed touchpoint paths and fractional credit. Paths are limited to interactions the system can observe and the selected key event.
- Data differences between reports and explorations
Google Analytics Help. Official explanation of differences caused by supported fields, filtering, retention, thresholds, modeling and processing. It covers GA4 surfaces, not every cross-platform discrepancy.
- About modeled key events
Google Analytics Help. Official description of modeled key events under observation gaps. Modeled values remain estimates and may differ across reporting surfaces and processing times.
Examples and exercises are illustrative unless attributed to a source. No independent expert review is claimed.
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