GA4 vs the Previous Universal Analytics

Universal Analytics (UA) is primarily session-based, whereas Google Analytics 4 (GA4) is event-based. Below is a more detailed breakdown of how these two models differ:

1. Data Model Focus

Universal Analytics (Session-Based)

  • The fundamental concept is a session, which is a group of user interactions (hits) that take place within a given timeframe (by default, 30 minutes of inactivity ends the session).
  • Within a session, different types of hits are recorded (pageviews, events, eCommerce transactions, etc.).
  • Metrics like “bounce rate,” “session duration,” and “session count” are central to reporting.

GA4 (Event-Based)

  • Each user interaction is tracked as an event, with parameters that describe that event.
  • GA4 does not rely on the session as the main organizing principle; it still tracks sessions but focuses on user interactions (events) as the key unit of measurement.
  • This event-driven approach allows more flexibility in how you record and analyze user behaviour, especially across multiple platforms (web, iOS, Android).

2. Flexibility in Data Collection

UA

  • Has predefined hit types (e.g., Pageview, Event, eCommerce, Social Interaction).
  • Each event hit is categorized with Category, Action, and Label plus associated value.
  • Custom event tracking often requires additional coding to collect anything beyond these standard parameters.

GA4

  • Every interaction is an event, with a name and any number of parameters (key-value pairs).
  • GA4 provides default event parameters (e.g., page_view, session_start) and lets you add custom parameters to events.
  • Offers an out-of-the-box set of automatically collected events and enhanced measurement events (e.g. scrolls, file downloads, outbound clicks), minimizing the need for manual setup.

3. User-Centric vs. Session-Centric Reporting

UA

  • Session data is central: user metrics are often aggregated at the session level.
  • Certain metrics, like average session duration, are direct outcomes of session-based logic.

GA4

  • Shifts to a user-centric model by focusing on each event. Instead of sessions driving the story, you get a more granular view of user journeys.
  • Can capture cross-device and cross-platform data more naturally in one property.
  • Encourages analysis of user engagement over time rather than just session-based metrics.

4. Reporting Differences

UA

  • Standard reports are organized around sessions, pages, and traffic sources.
  • Has numerous pre-built reports (Audience, Acquisition, Behaviour, Conversions).

GA4

  • Reports are more flexible and revolve around events and user engagement paths.
  • Uses “Explorations” (previously “Analysis Hub”) for custom funnels, path analysis, segment overlaps, and more advanced analytics.
  • Provides more advanced integration with BigQuery for deeper data analysis and machine learning.

5. Privacy and Future-Proofing

UA

  • Originally built in a world with fewer privacy constraints, focusing heavily on cookies, session IDs, and IP addresses for tracking.
  • Requires additional setup or add-ons for cookieless or privacy-friendly analysis.

GA4

  • Developed with evolving privacy regulations (GDPR, CCPA) and diminishing reliance on third-party cookies in mind.
  • Leans more on modeling and machine learning to fill in data gaps from privacy restrictions.
  • Uses an event-based structure that is more adaptable to privacy-safe measurement methods.

In Summary

  • Tracking Model: UA → session-based; GA4 → event-based.
  • Data Collection: UA has predefined hit types (pageviews, events); GA4 treats all interactions as events with flexible parameters.
  • Reporting: UA → standard, session-focused reports; GA4 → customizable, event-driven “Explorations.”
  • Future-Proofing: GA4 is built for privacy regulations and a cookieless future.

Ultimately, GA4’s event-driven model provides greater flexibility and depth in analyzing user interactions, enabling you to better understand user behaviour across devices and platforms.

Key differences between GA4's event-based and Universal Analytics' session-based tracking:

Event-Based (GA4):

  • Everything is tracked as an event – pageviews, clicks, scrolls, transactions, etc.
  • Each interaction is recorded independently with its own timestamp and parameters
  • More flexible data model that allows for richer user behaviour analysis
  • Better handles modern web behaviours like:
  • Single-page applications (SPAs)
  • Multiple device usage
  • Cross-platform journeys

For example, in GA4, a user journey might look like:

“event: page_view → event: scroll → event: file_download → event: begin_checkout → event: purchase”

 

Session-Based (Universal Analytics):

    • Centres around sessions as the main unit of measurement
    • Pageviews and interactions are grouped into sessions
    • Sessions expire after 30 minutes of inactivity by default
    • More rigid structure with hit types like:
      • Pageview
      • Events
      • Transactions
      • Social interactions

A similar journey in Universal Analytics would be organized like:

“Session 1: (pageview + event + event) → Session 2: (pageview + transaction)”

Key Practical Implications

  1. Data Collection
    • GA4: More granular data as each interaction stands alone
    • UA: Data is pre-organized into sessions, making some analyses simpler but less flexible
  1. Reporting
    • GA4: Can analyze individual user actions without session context
    • UA: Always ties metrics to sessions, making some cross-device analysis
    1. GA4: More sophisticated attribution models possible due to individual event tracking
      • UA: Attribution typically tied to sessions, which can miss cross-session behaviours
    1. Measurement Accuracy
      • GA4: Better handles modern web behaviours like background tabs and mobile app usage
      • UA: Can struggle with SPAs and cross-device journeys
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