Paid Search Incrementality Test Specification

Role: Lead Econometrician and Paid Media Scientist

Context

• Target Ad Network: {{primary_ad_network}}
• Core Test Hypothesis: {{test_hypothesis}}
• Historical Baseline Conversion Data: {{historical_conversion_volume}}
• Available Geo Clusters: {{test_geo_clusters}}
• Statistical Confidence Requirement: {{target_confidence_level}}
• Experimental Budget Cap: {{budget_allocation}}

Task

Synthesize historical conversion distributions and geographic parameters to author a comprehensive incrementality experiment specification, establishing control-treatment matching, statistical power calculations, and explicit pause/scale criteria for {{primary_ad_network}}.

Method

1. Analyze {{historical_conversion_volume}} to calculate baseline variance, seasonality indices, and minimum detectable effect (MDE).
2. Apply synthetic control matching across {{test_geo_clusters}} using Euclidean distance or correlation metrics on pre-period performance.
3. Formulate the explicit mathematical model for treatment effect estimation (Difference-in-Differences with synthetic controls).
4. Calculate required sample duration and statistical power based on {{target_confidence_level}} and expected spend.
5. Map out cell distribution, budget split, and negative targeting configurations within {{budget_allocation}}.
6. Formulate an anomaly detection protocol for external confounders during the active test period.
7. Define explicit post-test incremental ROAS (iROAS) and incremental Cost Per Acquisition (iCPA) calculation formulas.
8. Establish programmatic decision trees for permanent budget reallocation based on incrementality coefficients.

Constraints

• MUST express all statistical calculations with explicit variables, formulas, and baseline assumption ranges.
• MUST NOT use naive pre-post comparisons without synthetic control matching.
• Methodological steps MUST account for regional spillover and ad platform search cannibalization.
• All recommendations MUST operate strictly within {{budget_allocation}}.

Output format

• Executive Test Summary: 3-5 bulleted operational specifications.
• Geo-Matching & Power Calculations: Mathematical formula breakdown, MDE table, and cell split.
• Execution Protocol: Step-by-step launch, monitoring, and shutdown triggers.
• Incrementality Analysis Framework: Mathematical formulas for iROAS and statistical significance determination.

Self-review

• Ensure MDE and duration calculations realistically reflect {{historical_conversion_volume}}.
• Confirm synthetic control pairing methodology prevents geo contamination.
• Verify all formulas include clear variable definitions and statistical bounds.