We have been collecting data with GA4 since GP1 was introduced.
The plummeting session count is partly due to GP1, but it's also related to the transition from UA to GA4.
Session comparison between UA and GA4 is shown in the table below.
|
Metric
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UA
|
GA4
|
|
Session
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- Period of time a user is actively engaged with your website or app
- Has defined parameters for what may cause it to end, for example, a session will end when there has been more than a 30-minute period of inactivity, depending on the session timeout settings, the timestamp has been cut off at midnight, according to the timezone the view is set up in, or new campaign parameters are encountered.
- If a user comes back after a session timeout, it will start a new session.
- If the user is on the website when midnight arrives, a new session will be started.
- If a user picks up new campaign parameters while on the website, a new session will be started.
|
aka Session Start
- To determine the session that each event comes from, the
session_start event generates a session ID and Analytics associates the session ID with each subsequent event in the session
- A session will end when there has been more than a 30-minute period of inactivity, depending on the session timeout settings.
- Sessions aren't restarted at midnight or when new campaign parameters are encountered.
- If a user comes back after a session timeout, it will start a new session.
|
For non-session items, please refer to the following document.
Comparing metrics: Google Analytics 4 vs. Universal Analytics
We are investigating various causes and solutions to the issue of a sharp drop in sessions after the GP1 rollout, and believe that the issue is caused by GA4 characteristics, not data mis-mapping or missing.
GP1 is basically collecting data by tagging through GA4, which is different logic than GA3, which was previously collecting data.
Please note that due to the sunset of GA3, future data collection will be done in GA4.
