What is the default attribution model in GA4?

Google Analytics 4 uses data-driven attribution (DDA) as its default model. Unlike the old Universal Analytics default of last-click, DDA uses machine learning to distribute conversion credit across all touchpoints based on their actual contribution to the sale.

Can I still use last-click attribution in GA4?

Yes. While GA4 defaults to data-driven attribution, you can switch to last-click attribution in the Admin section under Attribution Settings. Google also provides last-click data in comparison reports so you can evaluate the difference between models.

Multi-Touch Attribution Models in GA4: The Right One for E-Commerce

Why Attribution Models Matter for E-Commerce

Imagine spending €10,000 per month on Google Ads, €3,000 on Facebook, and €2,000 on email marketing. Which channel actually drives your sales? The answer depends entirely on which attribution model you use in GA4.

A last-click model might tell you email is your best performer. A data-driven model might reveal that Facebook ads initiated 60% of the journeys that email later closed. Get this wrong, and you could cut the very channel feeding your entire funnel.

For most e-commerce businesses, the average customer interacts with 3 to 5 touchpoints before purchasing. Multi-touch attribution exists to give fair credit to each of those steps.

GA4 Attribution Models Explained

Data-Driven Attribution (Default)

GA4’s flagship model uses Google’s machine learning algorithms to analyze your actual conversion paths. It assigns fractional credit based on how much each touchpoint statistically contributed to a conversion.

Best for: Stores with high traffic volume (1,000+ conversions per month) and diverse channel mixes.

Example: A customer clicks a Google Shopping ad, then a retargeting Facebook ad, then converts via an email link. DDA might assign 45% credit to Google Shopping, 35% to Facebook, and 20% to email.

Last-Click Attribution

All credit goes to the final touchpoint before conversion. Simple, but misleading.

Best for: Businesses with very short sales cycles (impulse purchases under €30) or those just starting with analytics.

Limitation: In a study by Google, switching from last-click to data-driven attribution changed channel-level credit by 20 to 40% on average. That is a massive budget misallocation if you rely solely on last-click.

Linear Attribution

Every touchpoint gets equal credit. If there were four interactions, each receives 25%.

Best for: Brands that want a balanced overview without machine learning complexity.

Position-Based (U-Shaped)

Assigns 40% credit to the first interaction, 40% to the last, and distributes the remaining 20% across middle touchpoints.

Best for: E-commerce businesses that value both brand discovery and conversion equally.

How to Choose: A Practical Framework

Here is a quick decision matrix:

Monthly conversions over 1,000 → Use data-driven attribution. You have enough data for the algorithm to work accurately.
Monthly conversions between 300 and 1,000 → Start with position-based or linear, then compare against data-driven.
Monthly conversions under 300 → Use last-click or linear as a baseline. DDA may lack sufficient data.
Long sales cycle (7+ days) → Favor position-based to credit both awareness and closing channels.
Short sales cycle (under 48 hours) → Last-click or data-driven both work well.

Configuring Your Model in GA4

Go to Admin → Attribution Settings
Under Reporting Attribution Model, select your preferred model
Set your lookback window — 30 days for most e-commerce, 90 days for high-value or B2B products
Save and allow 24-48 hours for reports to update

At Lueur Externe, our analytics team regularly audits GA4 configurations for e-commerce clients, and misconfigured lookback windows are one of the most common — and costly — mistakes we find.

Compare Before You Commit

GA4’s Model Comparison report (under Advertising → Attribution) lets you see how conversions shift between models side by side. Run this comparison monthly. If data-driven and last-click show wildly different results, your upper-funnel channels are probably undervalued.

For example, one of our e-commerce clients discovered that their branded search campaigns were receiving 70% of last-click credit, while social media prospecting — which initiated most customer journeys — received only 5%. After switching to data-driven attribution and reallocating budget, their overall ROAS improved by 22% in three months.

Conclusion: Let Data Guide Your Budget

Multi-touch attribution is not an academic exercise — it directly determines where your marketing euros go. GA4 gives you powerful tools, but only if you configure them correctly and interpret the data with a clear strategy.

If you are running an e-commerce store and still relying on last-click attribution, you are almost certainly misallocating budget. Start with the model comparison report, test data-driven attribution, and iterate.

Need expert guidance? The certified analytics team at Lueur Externe can audit your GA4 setup, recommend the right attribution model for your business, and help you turn data into revenue. Get in touch today.