4.6.4 - Why Your Numbers Don't Match (Shopify vs. GA4 vs. Ads) (Difficulty: Advanced | Path: Scale)

Understanding Data Model Differences (Advanced)

What is it?

The simplest answer is that each platform counts sales differently based on its own self-interest. They use different 'attribution models'—rules for deciding who gets credit for a sale.

• Shopify: Your 'source of truth' for revenue. It reports on the last non-direct click. If a user clicks a Facebook ad, then later Googles you and clicks, Shopify gives 100% credit to Google.
• GA4 (Default): Uses a 'Data-Driven' model. It looks at *all* the touchpoints (the ad, the Google search, an email) and assigns partial credit to each one that contributed.
• Ad Platforms (Meta/Google): They are incentivized to take credit! They use a 'view-through' and 'click-through' window. If a user *saw* your ad (didn't even click!) and then bought within 1 day, the ad platform might take 100% credit.

Why is it important?

Understanding this stops you from making terrible decisions. If you only look at your Meta Ads manager, you might think it's driving 15 sales. If you only look at Shopify, you might think it's only driving 5. Neither is wrong; they're just answering a different question. Knowing this helps you see the whole picture.

Real-Life Example

A customer sees your Instagram ad (touchpoint 1), clicks it but doesn't buy. A week later, they click an email link (touchpoint 2). The next day, they Google your brand and click a link to buy (touchpoint 3).

• Shopify says: 1 sale from Google (last-click).
• GA4 says: 0.2 sales from Instagram, 0.5 from email, 0.3 from Google (data-driven).
• Meta (Facebook/Instagram) says: 1 sale from Instagram (click-through window).

All three platforms are reporting on the *same sale* but giving credit differently.

Common Pitfall

The pitfall is 'turning off' a channel because Shopify's last-click model says it's not working. You might turn off your Facebook ads (which are acting as touchpoint 1) and suddenly, your 'Google' sales (touchpoint 3) dry up. You've killed the top of your funnel without realizing it.