Conversion tracking is the process of measuring the conversions (purchases, signups, leads, downloads) produced by digital ad campaigns. Faulty conversion tracking corrupts every downstream optimization; the algorithm gets fed phantom signals and optimizes for the wrong outcome.
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Common problems:
- Double-counting · Tag Manager trigger duplicated
- Missing fires · some conversions go uncaught
- GA4 ↔ Google Ads mismatch · 10%+ gap between the two measurement systems
- Cross-domain breaks · payment page on a different domain truncates session
- iOS 14+ losses · App Tracking Transparency weakened iOS conversion signal
Verification: Tag Assistant + Google Ads ↔ GA4 cross-check + server-side GTM (if used) request log review.
Example: An e-commerce account where Google Ads reports 50 conversions while GA4 reports 35 has a 30% gap. Optimizing without diagnosing the source (cross-domain, double-count, attribution diff) produces wrong results.