Since Google Analytics 4 (GA4) launched in October 2020, many digital marketers and website owners have noticed significant differences between the data reported by GA4 and its predecessor, Universal Analytics (UA). But why doesn’t the data match? Let’s look at some of the key reasons.
Differences in data collection and processing
GA4 and UA differ fundamentally in how they collect, process and report data. While UA is based on sessions and pageviews, GA4 focuses on events and users. This means “equivalent” metrics between the two versions are calculated differently, which can lead to discrepancies.
Differences in attribution
UA uses a last non-direct click attribution model, meaning it attributes the conversion to the last traffic source that isn’t direct. GA4, on the other hand, uses a last-click attribution model, attributing the conversion to the last traffic source, even if it’s direct. This difference in attribution can lead to discrepancies in conversion data.
Differences in active user metrics
UA calculates daily, weekly and monthly active users based on sessions. GA4, however, takes a more user-centric approach, counting users who interact with the site in any way during the specified time period. This can result in discrepancies in active user data.
Event and pageview setup
In GA4, all interactions are treated as events, including pageviews. In UA, pageviews and events are handled differently. GA4 also automatically records certain events that UA doesn’t. These differences can lead to discrepancies in pageview and event data.
Session tracking
UA defines a session as a period of continuous interaction with the website that ends after 30 minutes of inactivity. GA4, on the other hand, considers a session to end after 30 minutes of inactivity or at midnight. This difference can result in discrepancies in session data.
In short, the differences between GA4 and UA stem from fundamental changes in how data is collected, processed and reported. Although this can lead to discrepancies, GA4 offers a more complete, user-centric view that can help marketers better understand user behavior and optimize their marketing strategies.
