google-ads-pmax-search-cannibalization-detector

PMax Search Cannibalization Detector

Framework for detecting and resolving Performance Max stealing Search campaign traffic. The #1 frustration in the PPC community -- PMax claims branded conversions making ROAS appear artificially high.

Quick Diagnosis

IS PMAX CANNIBALIZING YOUR SEARCH?
====================================

Step 1: Check PMax search terms report
        -> Many branded terms? --> PROBABLY YES

Step 2: Compare blended vs non-brand ROAS
        -> PMax ROAS 2x higher than Search? --> RED FLAG

Step 3: Check Search campaign metrics since PMax launch
        -> Search impressions/clicks dropped? --> CONFIRMED

RISK LEVELS:
+-- LOW:      <20% brand traffic in PMax search terms
+-- MEDIUM:   20-50% brand traffic -> monitor + consider exclusion
+-- HIGH:     50-70% brand traffic -> enable brand exclusion
+-- CRITICAL: >70% brand traffic -> PMax ROAS is misleading

Step 1: Data Collection

1A: PMax Search Terms Report

Use google_ads_run_gaql to retrieve PMax search terms:

SELECT campaign.name, search_term_view.search_term,
    metrics.impressions, metrics.clicks, metrics.cost_micros,
    metrics.conversions, metrics.conversions_value
FROM search_term_view
WHERE campaign.advertising_channel_type = 'PERFORMANCE_MAX'
AND segments.date DURING LAST_30_DAYS
ORDER BY metrics.impressions DESC
LIMIT 200

1B: Search Campaign Search Terms

SELECT campaign.name, search_term_view.search_term,
    metrics.impressions, metrics.clicks, metrics.cost_micros,
    metrics.conversions, metrics.conversions_value
FROM search_term_view
WHERE campaign.advertising_channel_type = 'SEARCH'
AND segments.date DURING LAST_30_DAYS
ORDER BY metrics.impressions DESC
LIMIT 200

1C: Campaign Performance per Channel Type

SELECT campaign.name, campaign.advertising_channel_type,
    campaign.status, metrics.impressions, metrics.clicks,
    metrics.cost_micros, metrics.conversions,
    metrics.conversions_value, metrics.search_impression_share
FROM campaign
WHERE segments.date DURING LAST_30_DAYS
AND campaign.status = 'ENABLED'
ORDER BY metrics.cost_micros DESC