1# GA4 Implementation Reference
2 
3Detailed implementation guide for Google Analytics 4.
4 
5## Contents
6- Configuration (data streams, enhanced measurement events, recommended events)
7- Custom Events (gtag.js implementation, Google Tag Manager)
8- Conversions Setup (creating conversions, conversion values)
9- Custom Dimensions and Metrics (when to use, setup steps, examples)
10- Audiences (creating audiences, audience examples)
11- Debugging (DebugView, real-time reports, common issues)
12- Data Quality (filters, cross-domain tracking, session settings)
13- Integration with Google Ads (linking, audience export)
14 
15## Configuration
16 
17### Data Streams
18 
19- One stream per platform (web, iOS, Android)
20- Enable enhanced measurement for automatic tracking
21- Configure data retention (2 months default, 14 months max)
22- Enable Google Signals (for cross-device, if consented)
23 
24### Enhanced Measurement Events (Automatic)
25 
26| Event | Description | Configuration |
27|-------|-------------|---------------|
28| page_view | Page loads | Automatic |
29| scroll | 90% scroll depth | Toggle on/off |
30| outbound_click | Click to external domain | Automatic |
31| site_search | Search query used | Configure parameter |
32| video_engagement | YouTube video plays | Toggle on/off |
33| file_download | PDF, docs, etc. | Configurable extensions |
34 
35### Recommended Events
36 
37Use Google's predefined events when possible for enhanced reporting:
38 
39**All properties:**
40- login, sign_up
41- share
42- search
43 
44**E-commerce:**
45- view_item, view_item_list
46- add_to_cart, remove_from_cart
47- begin_checkout
48- add_payment_info
49- purchase, refund
50 
51**Games:**
52- level_up, unlock_achievement
53- post_score, spend_virtual_currency
54 
55Reference: https://support.google.com/analytics/answer/9267735
56 
57---
58 
59## Custom Events
60 
61### gtag.js Implementation
62 
63```javascript
64// Basic event
65gtag('event', 'signup_completed', {
66  'method': 'email',
67  'plan': 'free'
68});
69 
70// Event with value
71gtag('event', 'purchase', {
72  'transaction_id': 'T12345',
73  'value': 99.99,
74  'currency': 'USD',
75  'items': [{
76    'item_id': 'SKU123',
77    'item_name': 'Product Name',
78    'price': 99.99
79  }]
80});
81 
82// User properties
83gtag('set', 'user_properties', {
84  'user_type': 'premium',
85  'plan_name': 'pro'
86});
87 
88// User ID (for logged-in users)
89gtag('config', 'GA_MEASUREMENT_ID', {
90  'user_id': 'USER_ID'
91});
92```
93 
94### Google Tag Manager (dataLayer)
95 
96```javascript
97// Custom event
98dataLayer.push({
99  'event': 'signup_completed',
100  'method': 'email',
101  'plan': 'free'
102});
103 
104// Set user properties
105dataLayer.push({
106  'user_id': '12345',
107  'user_type': 'premium'
108});
109 
110// E-commerce purchase
111dataLayer.push({
112  'event': 'purchase',
113  'ecommerce': {
114    'transaction_id': 'T12345',
115    'value': 99.99,
116    'currency': 'USD',
117    'items': [{
118      'item_id': 'SKU123',
119      'item_name': 'Product Name',
120      'price': 99.99,
121      'quantity': 1
122    }]
123  }
124});
125 
126// Clear ecommerce before sending (best practice)
127dataLayer.push({ ecommerce: null });
128dataLayer.push({
129  'event': 'view_item',
130  'ecommerce': {
131    // ...
132  }
133});
134```
135 
136---
137 
138## Conversions Setup
139 
140### Creating Conversions
141 
1421. **Collect the event** - Ensure event is firing in GA4
1432. **Mark as conversion** - Admin > Events > Mark as conversion
1443. **Set counting method**:
145   - Once per session (leads, signups)
146   - Every event (purchases)
1474. **Import to Google Ads** - For conversion-optimized bidding
148 
149### Conversion Values
150 
151```javascript
152// Event with conversion value
153gtag('event', 'purchase', {
154  'value': 99.99,
155  'currency': 'USD'
156});
157```
158 
159Or set default value in GA4 Admin when marking conversion.
160 
161---
162 
163## Custom Dimensions and Metrics
164 
165### When to Use
166 
167**Custom dimensions:**
168- Properties you want to segment/filter by
169- User attributes (plan type, industry)
170- Content attributes (author, category)
171 
172**Custom metrics:**
173- Numeric values to aggregate
174- Scores, counts, durations
175 
176### Setup Steps
177 
1781. Admin > Data display > Custom definitions
1792. Create dimension or metric
1803. Choose scope:
181   - **Event**: Per event (content_type)
182   - **User**: Per user (account_type)
183   - **Item**: Per product (product_category)
1844. Enter parameter name (must match event parameter)
185 
186### Examples
187 
188| Dimension | Scope | Parameter | Description |
189|-----------|-------|-----------|-------------|
190| User Type | User | user_type | Free, trial, paid |
191| Content Author | Event | author | Blog post author |
192| Product Category | Item | item_category | E-commerce category |
193 
194---
195 
196## Audiences
197 
198### Creating Audiences
199 
200Admin > Data display > Audiences
201 
202**Use cases:**
203- Remarketing audiences (export to Ads)
204- Segment analysis
205- Trigger-based events
206 
207### Audience Examples
208 
209**High-intent visitors:**
210- Viewed pricing page
211- Did not convert
212- In last 7 days
213 
214**Engaged users:**
215- 3+ sessions
216- Or 5+ minutes total engagement
217 
218**Purchasers:**
219- Purchase event
220- For exclusion or lookalike
221 
222---
223 
224## Debugging
225 
226### DebugView
227 
228Enable with:
229- URL parameter: `?debug_mode=true`
230- Chrome extension: GA Debugger
231- gtag: `'debug_mode': true` in config
232 
233View at: Reports > Configure > DebugView
234 
235### Real-Time Reports
236 
237Check events within 30 minutes:
238Reports > Real-time
239 
240### Common Issues
241 
242**Events not appearing:**
243- Check DebugView first
244- Verify gtag/GTM firing
245- Check filter exclusions
246 
247**Parameter values missing:**
248- Custom dimension not created
249- Parameter name mismatch
250- Data still processing (24-48 hrs)
251 
252**Conversions not recording:**
253- Event not marked as conversion
254- Event name doesn't match
255- Counting method (once vs. every)
256 
257---
258 
259## Data Quality
260 
261### Filters
262 
263Admin > Data streams > [Stream] > Configure tag settings > Define internal traffic
264 
265**Exclude:**
266- Internal IP addresses
267- Developer traffic
268- Testing environments
269 
270### Cross-Domain Tracking
271 
272For multiple domains sharing analytics:
273 
2741. Admin > Data streams > [Stream] > Configure tag settings
2752. Configure your domains
2763. List all domains that should share sessions
277 
278### Session Settings
279 
280Admin > Data streams > [Stream] > Configure tag settings
281 
282- Session timeout (default 30 min)
283- Engaged session duration (10 sec default)
284 
285---
286 
287## Integration with Google Ads
288 
289### Linking
290 
2911. Admin > Product links > Google Ads links
2922. Enable auto-tagging in Google Ads
2933. Import conversions in Google Ads
294 
295### Audience Export
296 
297Audiences created in GA4 can be used in Google Ads for:
298- Remarketing campaigns
299- Customer match
300- Similar audiences
301