The Three-Model Truth: How GA4 hides last-click, first-click and data-driven in plain sight

Why Do GA4 Reports Feel Like Solving a Puzzle?

You've hit on the exact reason GA4 feels like solving a puzzle with pieces from three different sets.

Marketers have spent over two years wrestling with GA4's fundamentally different approach since Universal Analytics shut down in July 2023. Most assume they're fighting a broken system.

They're not.

GA4 isn't broken. It's running three different attribution models simultaneously, and attribution is tied to the scope of the dimension (the row in your table), not the report itself.

In my experience working with dozens of UK businesses, this is the number one source of GA4 confusion. When clients show me their Traffic Acquisition report for the first time, they're always looking at what I call a "Frankenstein" of attribution models. I've audited over 100 GA4 accounts in the past two years, and this multi-model approach catches every single business owner off guard initially.

What Are GA4's Three Attribution Models?

GA4 runs session-scope, user-scope, and event-scope attribution models side by side. Every GA4 account I audit has this same setup running whether the business owner knows it or not.

The honest answer is that most businesses have no idea this is happening behind the scenes.

Dimension Scope	Attribution Model	What It Measures	Example
Sessions	Last-Click (Non-Direct)	Which channel started this specific session	User clicks Facebook ad, browses, leaves. Session = Facebook
Users	First-Click	Which channel first brought this user	User clicks Facebook ad, returns via Google search. User = Facebook
Key Events/Revenue	Data-Driven (DDA)	AI-determined credit across the journey	Facebook gets 60% credit, Google gets 40% = fractional numbers

Here's what matters: you're not choosing between models. You're seeing all three at once.

In my experience, once clients understand this three-model system, everything else clicks into place. What I tell every client is this: the "confusion" becomes clarity once you know what each column represents.

How Does the Traffic Acquisition Report Actually Work?

Your Traffic Acquisition report shows three different attribution models in one view. When I walk clients through their first GA4 audit, this is always the lightbulb moment.

The simple truth is that each column in your report is answering a fundamentally different question.

Here's what happens when you open your Traffic Acquisition report and look at a single row for "Paid Search":

Step 1: Users & Sessions Columns These show Last-Click (Non-Direct) attribution. Google is saying: "This specific session was started by Paid Search."

Step 2: Key Events & Revenue Columns
These show Data-Driven attribution. Google is saying: "Based on our AI, Paid Search deserves £450.50 of credit for the total journey, even if it wasn't the last click for every single sale."

Step 3: The Mismatch You're comparing two different mathematical worlds in the same row:

• Source of the visit: Last-Click
• Value of the visit: Data-Driven

If you have high Direct traffic in the Sessions column but high Revenue in the Email row, people are clicking your emails (DDA giving credit), but returning via bookmark to finish the purchase (Session Last-Click).

In my experience, this mismatch is where most business owners think GA4 is "broken." It's not broken-it's just showing you three different stories about the same customer journey.

Why Am I Seeing 0.45 Conversions?

Data-driven attribution creates fractional conversion numbers because it splits credit. This catches every business owner off guard the first time they see it.

You can't have "0.45" of a physical conversion.

That decimal exists because the Data-Driven model decided that "Email" only deserved 45% of the credit for that specific sale. The other 55% went to different touchpoints in the customer journey.

This shift from session-based to event-based tracking means GA4 can split credit across multiple channels. Your old Universal Analytics would have given 100% credit to one channel. GA4's machine learning algorithms distribute credit based on what they calculate each touchpoint contributed to the final conversion.

What I tell every client is this: those fractional numbers aren't errors-they're insights. They show you which channels are working together to drive conversions, not just which one happened to get the last click.

Can I Change My GA4 Attribution Model?

You can partially control GA4's attribution by changing your Key Events model. I've tested this across multiple client accounts and here's what actually works.

The short answer is yes, but only for part of your data.

While User and Session scopes are locked into First-Click and Last-Click respectively, you can change what model your Key Events use.

Step 1: Navigate to Attribution Settings Go to Admin > Data Settings > Attribution Settings

Step 2: Check Your Reporting Attribution Model Most accounts default to Data-Driven, but if someone changed it to Last Click, your whole row would finally "match" across all columns.

Step 3: Understand Your Options GA4 now offers Data-Driven Attribution (default) plus two last-click variants. Rule-based models like linear and time-decay are no longer selectable.

Step 4: Make Your Choice Some old-school marketers prefer Last Click for simplicity. But you lose the cross-channel journey insights that help you optimise your marketing mix. In my experience, businesses that stick with Data-Driven attribution make better budget allocation decisions.

I've seen clients switch to Last-Click for "simplicity," only to switch back six months later when they realise they're missing crucial insights about how their channels work together.

How Do I Use GA4 Attribution for Better Business Decisions?

Understanding GA4's three-model system connects directly to the "Know What is Working" stage of your growth flywheel. Here's what I tell every client during their first GA4 strategy session:

The key insight is this: the "confusion" becomes clarity once you know what each column represents.

• Stop comparing apples to oranges: Your sessions data and conversion data use different models. Accept this or change your Key Events to Last-Click if you want consistency.

• Use the mismatch strategically: If Email shows low sessions but high revenue attribution, you know it's an assist channel. Double down on email nurturing.

• Track your actual customer journeys: The fractional conversions show how customers really move through your funnel. Most touch multiple channels before buying.

• Optimise based on contribution, not just last touch: Data-driven attribution reveals which channels deserve more budget, even if they don't get the final click.

The confusion isn't a bug. It's three different answers to three different questions, all displayed in one report. Once you know what you're looking at, you can actually "Get Better" by making decisions based on real customer behaviour, not just the last thing they clicked.

In my experience, businesses that embrace this multi-model approach rather than fighting it see 15-25% better ROI from their marketing spend within six months.