Case Study: Diagnosing a 60% Attribution Gap in Paid Campaign Sales

An e-commerce company was facing a severe tracking mismatch between Google Ads and Matomo, casting doubt on their entire analytics setup. We conducted a full-stack audit and discovered that low cookie consent rates were causing Matomo to miss up to 60% of paid campaign sales. Our investigation ruled out technical issues, restored trust in Google Ads data, and provided a clear roadmap to recover lost attribution — unlocking visibility into over €14,000 in sales within just 2 weeks and helping protect €175K in annual revenue from misinformed decisions.

The Challenge of attribution discrepancy

A leading e-commerce company approached us with a serious tracking issue:
Their Google Ads dashboard showed more orders than their primary analytics tool Matomo – by a difference of 60%.

This discrepancy created doubt in the reliability of their entire tracking setup. The marketing team was unsure whether to trust Matomo at all, and the team considered Matomo’s reliability and migrating to another analytics tool. Confidence in campaign ROI was eroding fast — despite €13,000/month being spent on ads.

Client’s Tech Stack

Our Investigation into full stack of marketing & analytics

We were brought in to perform a full-stack audit of the client’s marketing and analytics implementation, including:

  • Matomo Analytics setup and attribution logic
  • Google Ads tracking templates and tag structure
  • Consent management setup (consentmanager) and user behavior
  • Google Tag Manager implementation
  • The ecommerce store built on Shopaware
  • Purchase funnel diagnostics using real test transactions

The core of our investigation involved data reconciliation, attribution tracing, and technical payload analysis across the entire stack.

TrackFunnels has been a fantastic resource for ConversionLab. We have been using them to troubleshoot tracking, implement GA4 and GTM setups, and handle Q&A for our e-commerce clients on Shopify. Their team is friendly, responsive, and truly knowledgeable. It’s a huge relief to have a reliable, go-to provider for any analytics issue that comes up.

Finge Holden
Founder & Conversion Rockstar, ConversionLab

We Discovered the cause of discrepancy

The analytics stack was technically sound – Matomo was not broken.

Instead, the discrepancy was due to:

  • Low consent rates (only 43% of users accepted cookies)
  • Matomo’s inability to persist attribution data for users who later returned and purchased without consent
  • Meanwhile, Google Ads was able to track cookieless conversions, leading to a wide attribution gap between the two platforms

We validated this by comparing:

  • Consent acceptance rate: 43%
  • Matomo sales attribution gap: 60%

The near-identical match confirmed the hypothesis

Insights Delivered Went Beyond The Symptoms

  • Ruled out major technical issues with Matomo
  • Clarified that attribution loss was due to GDPR-compliant cookieless tracking limitations
  • Restored trust in Google Ads data
  • Provided a GDPR-conscious roadmap to recover attribution accuracy:
  • Optimize consent banner to improve opt-in rates
  • Clean up dirty tracking templates in Google Ads
  • Set up goals and multi-attribution models in Matomo for deeper insights

Business Impact with an annual €175K revenue attribution

  • €14,670 in sales were being misattributed despite being generated by paid ads.
  • This represented a 60% underreporting of Google Ads revenue in the client’s analytics dashboard
  • The project prevented costly misjudgments, like pausing profitable campaigns or replacing analytics platforms unnecessarily
  • By restoring confidence in the current setup and enabling better attribution, the client can now optimize €13K/month ad spend with clarity
  • Estimated long-term value unlocked: €175K/year in correctly attributed revenue visibility

Need Help with Data Tracking & Attrubution?

TrackFunnels is an expert Data Tracking consulting.

If you’ve trouble tracking events for your B2B or eCommerce business whether in GA4 or any other analytics platform OR if you are facing attribution issues like UTM not properly passing through, schedule a free call with our founder.

Book a free consultation →

This Case Study Reflects How We Work

The client retained their analytics stack, regained trust in their data, and now has a plan to incrementally improve tracking accuracy all without making hasty platform migrations or cutting high-performing campaigns.

Our goal is to help teams make confident decisions with clean, reliable insights — not dashboards full of doubt.

This project reflects our core approach:

  • We go beyond just fixing symptoms — we find the root cause, even when it’s hidden behind layers of tools, tags, and assumptions.
  • Instead of recommending costly overhauls or platform migrations, we dive deep into the existing stack — auditing configurations, running controlled tests, and tracing real user journeys — to uncover what’s really happening beneath the numbers.
  • We blend marketing intuition with technical precision. We ask the uncomfortable questions. And we turn confusion into clarity — backed by data, not guesswork.

Do you currently face tracking challenges? Book a free consultation →

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