Google Analytics 4 (GA4).

The most important principle of GA4 is its event-based data model. A page view, a scroll to the bottom of the page, a click on a phone number, a submitted form — everything is an event with parameters. GA4 measures some events automatically; others have to be set up, usually via Google Tag Manager. Important events are marked as 'key events'; they are what used to be called goals.

Compared with Universal Analytics, reporting has changed considerably. Bounce rate was replaced by engagement rate (later reintroduced as bounce rate with the inverse logic), standard reports are leaner, and many questions can only be answered in the 'Explore' section or via Looker Studio. In addition, the standard version of GA4 keeps detailed data for at most 14 months — for year-on-year comparisons you have to set this option actively.

A key limit is consent. If a visitor declines analytics cookies, GA4 may not record them, or only to a limited extent. With Consent Mode, Google partly models the missing data, but the figures are then estimates. Anyone comparing GA4 values with data from a shop, a CRM or an ad account will therefore almost always see discrepancies.

For many SMEs, GA4 is more powerful than necessary and at the same time less meaningful than hoped. What matters is not having as many reports as possible but measuring a few events cleanly: enquiries, calls, bookings, purchases. Anyone who reliably knows just these four numbers makes better decisions than with a hundred unverified reports.