Case Study: SST Recovered 30% of Lost Conversions | Adslytics

The Starting Point

The client: a B2B SaaS company targeting marketing and analytics professionals. Monthly ad spend: £8,000 across Google Ads and Meta. The concern: Google Ads reported 40-45 trial sign-ups per month, but their product analytics (using Mixpanel) showed 60-65 trials starting per month. A 30-35% gap between what they were paying for and what was being attributed.

Additionally, their Meta campaigns were consistently underperforming compared to their Google Ads campaigns — an unusual pattern for their buyer persona which heavily uses both channels.

The Investigation

We analysed the discrepancy across three dimensions:

Ad Blocker Analysis

We compared Google Ads clicks to GA4 paid search sessions over 30 days:

Google Ads clicks: 4,200
GA4 paid search sessions: 2,940
Gap: 1,260 (30%)

For a B2B SaaS audience of marketing and analytics professionals, 30%+ ad blocker usage is entirely typical. The audience that most needs to understand analytics tools is also the audience most likely to block analytics tools.

Safari Cookie Analysis

We segmented the GA4 conversion data by browser:

Chrome trial sign-ups: 28 (consistent with expected conversion rate)
Safari trial sign-ups: 8 (significantly lower than expected given traffic share)

Safari users were converting at half the rate of Chrome users despite similar bounce rates. Investigation showed Safari users had a 14-21 day consideration cycle — they were starting a trial after multiple visits over 2-3 weeks. With Safari's 7-day cookie cap, these returning users appeared as new users on each visit and the final conversion was not attributed to the original ad click.

Meta Attribution Gap

Meta Events Manager showed low Event Match Quality (EMQ) of 3.2 for their trial sign-up event — meaning Meta could match only ~35% of their conversions to users. Meta's algorithm had very little signal to optimise on, leading to broader audience targeting and lower ROAS.

The Implementation

We implemented server-side GTM with:

Custom subdomain (analytics.theirclientdomain.com) on Google Cloud Run
GA4 routing through the server with server-side cookie setting (2-year expiration)
Meta CAPI via sGTM with hashed email (captured from the trial sign-up form) and fbp/fbc cookies
GA4 first-party cookie configuration to bypass Safari ITP

Results at 60 Days

Session and Event Recovery:

GA4 sessions from paid search increased from 2,940/month to 3,780/month (+28.6%)
Trial sign-up events in GA4 increased from 43/month to 62/month (+44%)

Attribution Recovery:

Google Ads reported conversions increased from 42/month to 58/month (closer to Mixpanel's 60-65)
Remaining 3-5 gap = trials from channels other than paid ads (organic, direct) — now tracking correctly

Meta Performance:

Meta Event Match Quality improved from 3.2 to 7.8 after including hashed email in CAPI events
Meta trial sign-up cost per acquisition decreased 31% over 8 weeks as the algorithm found better audiences with improved signal

Smart Bidding Impact (Google Ads):

Target CPA campaigns improved by 18% in conversion efficiency after 6 weeks of recalibration on the fuller conversion data

Key Lessons

Cross-referencing ad clicks to GA4 sessions is a fast way to quantify your ad blocker impact — a 30% gap demanded action
Browser-segmented conversion rate analysis reveals Safari ITP impact specifically
Meta CAPI with hashed email is a game-changer for Event Match Quality — nothing else moves that needle as effectively
Allow 6-8 weeks for Smart Bidding to fully recalibrate on improved conversion data before evaluating performance changes

Summary

This case study framework shows a typical server-side tracking improvement pattern: significant session and conversion recovery from ad blocker traffic, Safari ITP attribution repair, and Meta campaign performance improvement from CAPI with hashed email. The combined effect on total business is substantial — 30% more conversions attributed to the channels that drove them.

See our Server-Side Tracking service for implementation.

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