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ADS·Google Ads·warning

Inconsistent Attribution Models

Different conversion actions in this account use different attribution models. Some Data-Driven, some Last-Click, some Position-Based. When these actions roll up into the same campaign or goal report, the displayed conversion value mixes attribution logic in ways that make period-over-period comparison and bidding decisions unreliable.

CL
By Christopher LandaverdeCreator of AdLint · ad-tech tracking specialistUpdated

Why It Matters

Google Ads lets each conversion action pick its attribution model independently. This flexibility is useful (DDA for high-volume actions, simpler models for low-volume ones) but produces silent reporting inconsistency: a "total conversion value" that is the sum of values calculated under different attribution logics is not a meaningful number. Campaigns reporting against mixed-attribution goals show metrics that move not because performance changed, but because the relative volume of differently-attributed actions shifted. Bidding strategies optimise against the mixed signal and produce inconsistent CPA across similar campaigns.

How To Fix It

  1. List every enabled Primary conversion action and its current attribution model (Tools & Settings → Measurement → Conversions → Attribution column).
  2. Decide the account-level attribution philosophy: either standardise on Data-Driven (preferred when every Primary has sufficient volume), Position-Based (a reasonable middle ground), or Last-Click (simplest, most rule-based).
  3. Update each Primary action to use the chosen model.
  4. Document the chosen model in the team's measurement playbook so future conversion actions inherit it by default.
  5. Annotate the change date for period-over-period reporting clarity.

Example

Configuration
Problem:
  Purchase: Data-Driven
  Lead: Last-Click
  Demo Request: Position-Based
Fix: standardise on Data-Driven (or document why each is different).
For Your Client Report

Google Ads Primary conversion actions configured with mixed attribution models. Google's attribution documentation, mixed models produce report-level totals that combine attribution logics in ways that cannot be meaningfully compared period-over-period or used by Smart Bidding without distortion. Fix: standardise Primary actions on a single attribution model (preferably Data-Driven where volume supports it) and document the choice in team materials. Source: support.google.com/google-ads/answer/6394265.

Drop this paragraph into your client deliverable. Sources back to the canonical platform documentation linked below.

References

  1. [1]Google Ads. About attribution models

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