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Universal Analytics vs GA4

Change in data model means that session related information is going to be collected within event parameters and will no longer be an independent data structure

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Session information in GA4​

  • Data collection basis will be events NOT sessions
  • Each line in the data will correspond to an event NOT a session
  • Each event will have two session related parameters:
    • ga_session_id: similar to visitId - collected with each event triggered within a session
    • ga_session_number: similar to visitNumber - a default collected parameter with each event within a session which identifies the ordinal position of a session as it relates to a user i.e. is it the users 1st or nth session
  • Session start will be marked by an event called session_start
    • If 30 minutes pass without an event the next event the user generates will also trigger a new session_start event
  • Change in day or traffic acquisition (e.g. change medium) DO NOT trigger a new session_start even
    • If session happens over 2 days it will count in both days session counts
    • The session counts between GA360 and GA4 will differ somewhat - see screenshots on right
  • There will no longer be any session scope metrics - see data model on the right
    • User Properties - equivalent to user scope dimensions
    • Parameters - equivalent to hit scope dimensions

Session metrics in GA4​

Session-related metrics are derived from the automatically collected ‘session_start’ event:

  • Sessions: nr of times session_start event was triggered
  • Engaged sessions: number of sessions lasting more than 10 sec OR had min. 1 conversion event OR had min. 2 pageviews
    • The old bounce rate would have been somewhat comparable to ([sessions] - [engaged sessions]) / [sessions]
  • Engaged sessions per user: [nr of engaged sessions] / [nr of users]
  • Average session duration: Average length of time of all sessions
    • Session Duration: the time span between the first and last event in the session Events per session: [nr of events] / [nr of sessions]
  • GA4 will no longer have bounced sessions
    • Bounce Rate metric will no longer be available
  • Conversions in GA4 are not fully equivalent with Goals in GA360
    • Conversions will count total events which match the conversion rules
    • Goals count sessions in which a specific event or action happened at least once BUT will not convert again if the action is repeated
    • Goal conversion numbers and GA4 conversion numbers will differ

Events in GA4​

As opposed to Universal Analytics (GA360) the basis of data collection in GA4 is an event. This means that each line of data in BQ will correspond to an event.

As opposed to GA360 events do not follow the category-action-label naming convention

  • Instead of ec-ea-el we now have event parameters: text and value with a limit of 50 each per property
  • Registered text parameters = event scoped custom dimension
  • Registered numeric parameters = event scoped custom metric

A single event can have

  • max. 25 parameters associated with it in the GA4 interface
    • Events can have different parameters from each other
  • Limitless number of parameters in BQ

There can be 500 distinct events per property

As opposed to GA360 every user interaction triggers an event and there is no differentiation between event types in the same way GA360 differentiated between types of this.

  • A page view is an event NOT a page type hit

Any event can be marked as a conversion event

  • Note: conversion events are NOT the same as goals
    • Conversions = count of specific event in a given time frame, not necessarily tied to a session
    • Goal = unique event per session

It is possible to calculate events/session in the Engagement tab (see screenshot)