Technical Deep Dives

    Incrementality testing: proving marketing causation through experimentation

    12 min read
    Incrementality testing: proving marketing causation through experimentation

    Attribution tells you what happened. Incrementality testing tells you what your marketing caused. This guide covers how to design and run incrementality experiments.

    incrementality
    experimentation
    testing
    causation
    measurement

    Attribution tells you what happened. Incrementality testing tells you what your marketing caused. The difference can be worth millions in misallocated spend.

    What is incrementality testing?

    Incrementality testing uses experimental design to isolate the causal impact of marketing activities. By comparing outcomes in test versus control groups, you measure what your marketing actually caused.

    Types of incrementality tests

  1. Geo-based lift tests - Compare regions with/without marketing
  2. Conversion lift studies - Platform-run holdout experiments
  3. Ghost ads/PSA tests - Show placebo ads to control groups
  4. Matched market tests - Compare similar markets with different treatments
  5. Designing effective geo-tests

    Key requirements:

  6. Sufficient test duration (4-8 weeks minimum)
  7. Matched market selection
  8. Clean holdout (no other major changes)
  9. Adequate sample size for statistical power
  10. Interpreting results

    Calculate:

  11. Absolute incremental lift
  12. Incremental cost per acquisition
  13. True incremental ROAS
  14. Statistical confidence intervals
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