Google Analytics 4 Complete Guide: Setup, Events, Reports, and AI

Why Google Analytics 4 is a complete rewrite

Google Analytics 4 (GA4) is not an upgrade to Universal Analytics—it's a new platform built from scratch. The old model tracked pageviews and sessions. GA4 tracks events and users across web and app, with AI-driven insights built in.

If you're still on Universal Analytics, migration is mandatory: Google shut it down on July 1, 2023. If you haven't set up GA4, you're flying blind.

Core GA4 fundamentals

GA4 is event-based, not session-based.

What does this mean?

1. Every interaction is an event: page view, button click, video play, form submission, purchase.
2. Events have parameters: the page URL, button name, video title, form ID.
3. Users are tracked across devices and sessions. If you visit on mobile, then desktop, GA4 recognizes it's the same person.
4. Sessions are derived from events, not the foundation. GA4 reassembles user journeys from individual events.

This shift lets GA4 answer questions Universal Analytics couldn't: "Which exact button do users click before leaving?" "What's the sequence of events that leads to a purchase?" "Which users are likely to churn?"

Setting up GA4 from scratch

If you're new to GA4, here's the path:

1. Create a Google Analytics property: Log into Google Analytics, create a new property, select "Web" as the platform.
2. Install the measurement ID: GA4 gives you a measurement ID (G-XXXXXXXX). Install it via Google Tag Manager or direct snippet.
3. Configure Google Tag Manager (optional but recommended): Set up GTM first if you have complex tracking. GTM makes GA4 configuration easier and more maintainable.
4. Enable enhanced measurement: Out of the box, GA4 tracks page views, scrolls, outbound clicks, and video engagement. Enable all these in settings.
5. Create conversion goals: Decide what "conversion" means—form submissions, purchases, newsletter signups. Set these up early.
6. Set up audience definitions: Segment users by behavior (e.g., "users who viewed pricing page but didn't convert"). Use these in reports and ads.

Events and conversions: the new language

In GA4, you speak in events and conversions.

Events are the building blocks:

1. page_view: a page loads.
2. scroll: user scrolls past 90% of the page.
3. click: user clicks a link or button (if tracked).
4. view_search_results: a search query is executed.
5. view_item: a product or article is viewed.
6. add_to_cart: item added to cart (e-commerce).
7. purchase: transaction completed.
8. form_submit: a form is submitted.
9. video_play, video_complete: video engagement.

You can create custom events too. For example, "newsletter_signup" or "whitepaper_download."

Conversions are marked events that matter to your business:

You decide which events are conversions. If "form_submit" happens on your contact form, mark it as a conversion. GA4 will track how many users convert, when, and what they did before converting.

Main GA4 reports and what they tell you

Here are the reports you'll use most:

GA4's AI-driven insights

GA4 includes predictive AI features:

1. Predictive audiences: GA4 identifies users likely to purchase, churn, or spend high value. You can send these segments to Google Ads for retargeting.
2. Anomaly detection: GA4 flags unusual spikes or drops in traffic, conversions, or engagement. It tells you when something's wrong.
3. Insights (automated): GA4 highlights the most important changes in your data without you asking.

These aren't magic—they're statistical models trained on your historical data. But they save time spotting trends and problems.

Connecting GA4 to Google Ads

If you run Google Ads, link your GA4 property to your Ads account:

1. Link the accounts: In GA4 settings, connect your Google Ads account.
2. Define conversions: Mark which GA4 events count as conversions for Ads (e.g., purchases).
3. Use audiences in Ads: GA4 automatically creates audiences of your converters, high-value users, and at-risk users. Send these to Ads for retargeting.
4. Track ROAS: GA4 calculates return on ad spend (ROAS) if you link Ads and enable ecommerce tracking.

Common GA4 setup mistakes

Mistake #1: Not configuring conversions

GA4 won't automatically recognize your business goals. You must mark events as conversions. If you don't, you can't track goal completion or ROI.

Mistake #2: Mixing web and app data without filtering

If you have a website and mobile app, GA4 can combine them in one property. But if they have different business models, create separate properties to avoid noise.

Mistake #3: Over-tracking; creating too many custom events

GA4 is powerful, but every custom event is a maintenance burden. Track what matters: conversions, key user actions, segments. Skip the noise.

Mistake #4: Ignoring privacy settings and user consent

GA4 respects privacy frameworks like GDPR. Configure consent mode so GA4 stops tracking if the user doesn't consent. Otherwise, you're breaking the law.

Migrating from Universal Analytics

If you're moving from UA to GA4:

1. Set up GA4 in parallel with UA. Keep both running for 3–6 months so you can compare.
2. Reconfigure conversions. UA and GA4 define conversions differently.
3. Redefine segments. GA4 uses events; UA used sessions. Your segments will change.
4. Update dashboards and reports. Your custom reports in UA won't work in GA4.
5. Train your team. GA4 is different enough that your team needs to learn it.

Data privacy and GDPR

GA4 respects privacy. Here's what you need to know:

1. Anonymization: GA4 can anonymize IP addresses so you're not storing user location.
2. Consent mode: If a user doesn't consent, GA4 stops tracking. It still sends anonymized data for aggregation.
3. Data retention: Set how long GA4 keeps user-level data (default is 14 months). Shorter retention = better privacy.
4. User deletion: Users can request deletion. GA4 supports the deletion API so you can honor GDPR/CCPA requests.

The bottom line

GA4 is more powerful than Universal Analytics—but it requires setup. Spend time configuring conversions, linking to Ads, and understanding events. The upside is clear: you'll understand user behavior better, optimize faster, and make data-driven decisions.

If you haven't migrated yet, do it today. The sooner you have clean GA4 data, the sooner you can act on it.