GA4 Implementation Reference

Detailed implementation guide for Google Analytics 4.

Contents

• Configuration (data streams, enhanced measurement events, recommended events)
• Custom Events (gtag.js implementation, Google Tag Manager)
• Conversions Setup (creating conversions, conversion values)
• Custom Dimensions and Metrics (when to use, setup steps, examples)
• Audiences (creating audiences, audience examples)
• Debugging (DebugView, real-time reports, common issues)
• Data Quality (filters, cross-domain tracking, session settings)
• Integration with Google Ads (linking, audience export)

Configuration

Data Streams

• One stream per platform (web, iOS, Android)
• Enable enhanced measurement for automatic tracking
• Configure data retention (2 months default, 14 months max)
• Enable Google Signals (for cross-device, if consented)

Enhanced Measurement Events (Automatic)

Event	Description	Configuration
page_view	Page loads	Automatic
scroll	90% scroll depth	Toggle on/off
outbound_click	Click to external domain	Automatic
site_search	Search query used	Configure parameter
video_engagement	YouTube video plays	Toggle on/off
file_download	PDF, docs, etc.	Configurable extensions

Recommended Events

Use Google's predefined events when possible for enhanced reporting:

All properties:

• login, sign_up
• share
• search

E-commerce:

• view_item, view_item_list
• add_to_cart, remove_from_cart
• begin_checkout
• add_payment_info
• purchase, refund

Games:

• level_up, unlock_achievement
• post_score, spend_virtual_currency

Reference: https://support.google.com/analytics/answer/9267735

---

Custom Events

gtag.js Implementation

// Basic event
gtag('event', 'signup_completed', {
  'method': 'email',
  'plan': 'free'
});

// Event with value
gtag('event', 'purchase', {
  'transaction_id': 'T12345',
  'value': 99.99,
  'currency': 'USD',
  'items': [{
    'item_id': 'SKU123',
    'item_name': 'Product Name',
    'price': 99.99
  }]
});

// User properties
gtag('set', 'user_properties', {
  'user_type': 'premium',
  'plan_name': 'pro'
});

// User ID (for logged-in users)
gtag('config', 'GA_MEASUREMENT_ID', {
  'user_id': 'USER_ID'
});

Google Tag Manager (dataLayer)

// Custom event
dataLayer.push({
  'event': 'signup_completed',
  'method': 'email',
  'plan': 'free'
});

// Set user properties
dataLayer.push({
  'user_id': '12345',
  'user_type': 'premium'
});

// E-commerce purchase
dataLayer.push({
  'event': 'purchase',
  'ecommerce': {
    'transaction_id': 'T12345',
    'value': 99.99,
    'currency': 'USD',
    'items': [{
      'item_id': 'SKU123',
      'item_name': 'Product Name',
      'price': 99.99,
      'quantity': 1
    }]
  }
});

// Clear ecommerce before sending (best practice)
dataLayer.push({ ecommerce: null });
dataLayer.push({
  'event': 'view_item',
  'ecommerce': {
    // ...
  }
});

---

Conversions Setup

Creating Conversions

1. Collect the event - Ensure event is firing in GA4
2. Mark as conversion - Admin > Events > Mark as conversion
3. Set counting method:
   • Once per session (leads, signups)
   • Every event (purchases)
4. Import to Google Ads - For conversion-optimized bidding

Conversion Values

// Event with conversion value
gtag('event', 'purchase', {
  'value': 99.99,
  'currency': 'USD'
});

Or set default value in GA4 Admin when marking conversion.

---

Custom Dimensions and Metrics

When to Use

Custom dimensions:

• Properties you want to segment/filter by
• User attributes (plan type, industry)
• Content attributes (author, category)

Custom metrics:

• Numeric values to aggregate
• Scores, counts, durations

Setup Steps

1. Admin > Data display > Custom definitions
2. Create dimension or metric
3. Choose scope:
   • Event: Per event (content_type)
   • User: Per user (account_type)
   • Item: Per product (product_category)
4. Enter parameter name (must match event parameter)

Examples

Dimension	Scope	Parameter	Description
User Type	User	user_type	Free, trial, paid
Content Author	Event	author	Blog post author
Product Category	Item	item_category	E-commerce category

---

Audiences

Creating Audiences

Admin > Data display > Audiences

Use cases:

• Remarketing audiences (export to Ads)
• Segment analysis
• Trigger-based events

Audience Examples

High-intent visitors:

• Viewed pricing page
• Did not convert
• In last 7 days

Engaged users:

• 3+ sessions
• Or 5+ minutes total engagement

Purchasers:

• Purchase event
• For exclusion or lookalike

---

Debugging

DebugView

Enable with:

• URL parameter: ?debug_mode=true
• Chrome extension: GA Debugger
• gtag: 'debug_mode': true in config

View at: Reports > Configure > DebugView

Real-Time Reports

Check events within 30 minutes: Reports > Real-time

Common Issues

Events not appearing:

• Check DebugView first
• Verify gtag/GTM firing
• Check filter exclusions

Parameter values missing:

• Custom dimension not created
• Parameter name mismatch
• Data still processing (24-48 hrs)

Conversions not recording:

• Event not marked as conversion
• Event name doesn't match
• Counting method (once vs. every)

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Data Quality

Filters

Admin > Data streams > [Stream] > Configure tag settings > Define internal traffic

Exclude:

• Internal IP addresses
• Developer traffic
• Testing environments

Cross-Domain Tracking

For multiple domains sharing analytics:

1. Admin > Data streams > [Stream] > Configure tag settings
2. Configure your domains
3. List all domains that should share sessions

Session Settings

Admin > Data streams > [Stream] > Configure tag settings

• Session timeout (default 30 min)
• Engaged session duration (10 sec default)

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Integration with Google Ads

Linking

1. Admin > Product links > Google Ads links
2. Enable auto-tagging in Google Ads
3. Import conversions in Google Ads

Audience Export

Audiences created in GA4 can be used in Google Ads for:

• Remarketing campaigns
• Customer match
• Similar audiences