Google Analytics 4

The founder who discovered £180,000 in hidden revenue

In 2022, the founder of a UK-based e-learning platform was convinced that YouTube was his best acquisition channel. He could see the view counts. He could see the subscriber growth. He felt the momentum.

His developer spent half a day properly configuring GA4 — setting up events, linking Google Ads, configuring conversion paths.

The data told a completely different story.

YouTube was generating 34% of website traffic but only 4% of purchases. His email list — which he'd been neglecting, sending roughly one email per month — was generating 8% of traffic and 31% of purchases. His Google Search ads, which he'd considered pausing to cut costs, were generating 19% of traffic and 48% of purchases.

He'd been investing effort and budget based on what he felt was working. The actual data was pointing somewhere else entirely.

Recalibrating around the data — more email, sustained Google Search, less YouTube — added an estimated £180,000 in annual revenue.

(Illustrative scenario based on patterns common in marketing analytics. Specific figures are representative of real-world outcomes — not a verified account of a specific named company.)

What GA4 is and how it works

Google Analytics 4 (GA4) is Google's current web analytics platform. It replaced Universal Analytics (UA) — standard properties were sunset in July 2023, with UA 360 following in July 2024 — and works fundamentally differently from its predecessor.

The core shift: from sessions to events

Universal Analytics was session-based. A "session" was a visit; everything happened within sessions.

GA4 is event-based. Every interaction is an event:

• Page view → an event
• Button click → an event
• Video play → an event
• Form submission → an event
• Purchase → an event (with revenue value)

This makes GA4 far more flexible — you can measure anything — but also more complex. Understanding what events you're tracking and what they mean is essential.

Key dimensions in GA4:

The acquisition reports: where your traffic comes from

The most important question in marketing analytics: where are my customers coming from?

GA4's Acquisition reports answer this at three levels:

Traffic Acquisition — the session source (what brought this particular session?) User Acquisition — the first-touch source (what first brought this user to the site?)

Both matter, for different purposes. User acquisition tells you which channels are introducing new people. Traffic acquisition tells you which channels drive returning visits and purchase-intent behaviour.

Default channel groupings in GA4:

The "Unassigned" problem: A large proportion of "Unassigned" or "Direct" traffic usually indicates a UTM tagging gap — campaigns are running without source tags, making their traffic invisible in channel groupings. If you see more than 15–20% in Direct/Unassigned, investigate your UTM implementation.

The engagement and conversion reports

Beyond where traffic comes from, GA4 shows what users do:

Engagement overview:

• Engaged sessions: Sessions that lasted > 10 seconds, had a conversion, or had 2+ page views (GA4's replacement for bounce rate)
• Engagement rate: % of sessions that were engaged (inverse of bounce rate)
• Average engagement time: Time users are actively on the site (not just the tab being open)

Funnel exploration: One of GA4's most powerful features. Define a multi-step funnel (e.g., Landing page → Product page → Add to cart → Checkout → Purchase) and see the drop-off at each step.

Reading a funnel like this, you can immediately see where to invest optimisation effort: the 68% who visit a product page but only 31% add to cart is a significant drop. Is the price wrong? Is the product page unconvincing? Is the CTA unclear? That's where the testing budget should go.

Setting up GA4 correctly

A GA4 property is only as useful as its configuration. Common setup failures:

Not defining conversions: GA4 tracks events automatically, but you must mark specific events as conversions (goals). Without marking "Purchase" or "Lead Form Submit" as conversions, your conversion rate reports are empty.

Not linking Google Ads: Without linking, paid search traffic appears as "Unassigned" and you can't see campaign-level performance in GA4.

Not using UTM tags: Without UTM parameters on all ad, email, and social links, traffic arrives as "Direct" — invisible in channel reports.

Setting up GA4 through Google Tag Manager (GTM): The professional standard. GTM lets you manage all tracking tags (GA4, Meta Pixel, LinkedIn Insight Tag, etc.) from one interface without touching website code for each change.

Essential GA4 events to track as conversions:

• purchase (for e-commerce)
• generate_lead (for lead generation)
• sign_up (for trial/registration)
• contact (form submissions)
• Any custom events specific to your business goals

Reading GA4 intelligently

Segment before concluding. Averages hide everything. A 3% conversion rate that's 7% for mobile and 0.8% for desktop is a mobile-vs-desktop problem, not a "3% conversion rate" situation. Always segment by device, source, audience, geography before drawing conclusions.

Compare time periods. Week-over-week and year-over-year comparisons reveal trends. A 15% drop in organic traffic this week compared to last week is noise; a 15% drop compared to the same week last year is a signal worth investigating.

Look for patterns, not single data points. One day of low conversions is irrelevant. Three consecutive weeks of declining conversion rate from paid search is actionable.

The "so what?" test. For every metric you look at, ask: what decision would be different if this number were 50% higher? If the answer is "nothing," you're looking at a vanity metric.

Back to the founder

The £180,000 wasn't hidden in a new channel or a new campaign — it was already there, in his email list and his Google Search ads, going unmeasured and therefore uninvested in. He'd been making decisions based on what felt like momentum (YouTube view counts, subscriber growth) while the actual conversion data pointed somewhere else entirely. Half a day of proper GA4 configuration — events set up, Google Ads linked, conversion paths defined — made the invisible visible. The revenue wasn't created by fixing the tracking; it was created by the decisions that accurate tracking made possible. The measurement was always the prerequisite. The money was always there; the measurement wasn't.

Key takeaways

• GA4 is event-based. Every interaction is an event; you define which events are conversions. Properly configured conversions are the foundation of useful analytics.
• Acquisition reports tell you where customers come from. User acquisition for first-touch analysis; Traffic Acquisition for channel performance. UTM tags are mandatory to see paid and email traffic correctly.
• Funnel explorations reveal where to optimise. Define your conversion path, see drop-off at each step, and direct testing budget to the biggest gaps.
• GA4 undercounts — use it for relative comparison. Depending on your audience and geography, GA4 may undercount a significant share of sessions — estimates range from 10% to 40%+ in markets with strict privacy regulation (EU consent requirements and ad blockers being the main factors). Compare channels against each other, not against absolute totals.
• Data quality requires setup and maintenance. Conversions defined, Google Ads linked, UTMs on all paid links, quarterly audits — these are the foundation of trustworthy data.