This table provides a concise overview of each metric, its definition, and the main caveats to consider when interpreting the data. It's important to keep these limitations in mind when analyzing GA4 data and making business decisions based on these metrics.
| Metric | Definition | Caveats |
|---|---|---|
| Active Users | The number of distinct users who have initiated at least one event or user engagement in the specified date range. | - May overcount due to cookie-based tracking - Cross-device usage can lead to multiple counts of single individuals |
| New Users | The number of distinct users who triggered a first_open event (for apps) or first_visit event (for websites) within the specified date range. | - Based on first-party cookies, which can be cleared or blocked - May miscount returning users on new devices as new |
| Returning Users | Users who have initiated at least one previous session on your website or app. | - Dependent on cookie persistence - Cross-device limitations may undercount actual returning users |
| Sessions | The period of time a user is actively engaged with your website, app, etc. By default, a session lasts until there's 30 minutes of inactivity. | - Definition can vary based on GA4 settings - May split artificially due to time-outs or midnight crossovers |
| Engaged Session | A session that meets at least one of the following criteria: 1. Lasts 10 seconds or longer 2. Has at least one conversion event 3. Has 2 or more page or screen views |
- May not fully capture user engagement if users quickly navigate without meaningful interaction - Can be influenced by session timeout settings - Users may trigger engaged sessions without genuine interest (e.g., accidental clicks) |
| Session Source | The origin of a session, such as a search engine or referring website. | - Last non-direct click attribution model may not reflect full customer journey - Can be affected by direct traffic overriding previous sources |
| Average Engagement Time | The average length of time that the app was in the foreground or the website was in focus. | - Can be inflated by users leaving tabs open - Doesn't distinguish between quality and passive engagement |
| Event | Any interaction that can be measured independently from a pageview or screenview. | - Dependent on correct implementation and consistent tracking - May miss events due to ad-blockers or tracking opt-outs |
| Landing Page | The page where a user enters your website. | - May not reflect true entry point in cross-device journeys - Affected by redirect chains or single-page applications |
| User Retention | The percentage of active users on a given day who were still active users on a later day. | - Accuracy decreases over time due to cookie issues - Cross-device usage can lead to underestimation |
