Analytics Tracking - Implementation & Auditing

Category: Marketing Tags: GA4, Google Tag Manager, event tracking, conversion tracking, UTM, analytics audit, consent mode

Overview

Analytics Tracking is the implementation layer for marketing measurement. Bad tracking is worse than no tracking -- duplicate events, missing parameters, unconsented data, and broken conversions lead to decisions based on bad data. This skill covers building tracking right the first time and finding what is broken when it is not.

This skill handles implementation only. For analyzing campaign performance data, use campaign-analytics. For product analytics and in-app behavior, use the product-team skills.

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Clarify First

Before building the tracking plan, confirm these inputs. If any is unknown or vague, ASK — do not assume:

• Operating mode — build from scratch, audit existing, or debug a specific issue (selects the entire workflow)
• Platform stack — GA4, GTM, and which ad platforms (Google Ads / Meta / LinkedIn) (drives implementation + conversion tracking setup)
• Key conversions + funnel events — the user actions that matter to the business (drives event taxonomy + conversion configuration)
• Region / consent requirements — EU/EEA users present? (determines whether Consent Mode v2 is required)

Stop rule: ask only the 2-3 that most change the output. If the user says "just draft it," proceed and list your assumptions at the top of the artifact.

Operating Modes

Mode 1: Build From Scratch

No analytics in place. Build the tracking plan, implement GA4 + GTM, define event taxonomy, configure conversions.

Mode 2: Audit Existing Tracking

Tracking exists but data cannot be trusted. Audit coverage, identify gaps, clean up duplicates, fix consent issues.

Mode 3: Debug Specific Issues

Events are missing, conversions do not match, GTM preview shows fires but GA4 does not record. Structured debugging workflow.

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Event Taxonomy Design

Get this right before touching GA4 or GTM. Retrofitting taxonomy is painful and expensive.

Naming Convention

Format: object_action (snake_case, past tense verb)

Correct	Wrong	Why Wrong
form_submitted	submitForm	camelCase, verb-first
plan_selected	clickPricingPlan	Implementation detail, not user action
video_started	VideoStart	PascalCase, inconsistent tense
checkout_completed	purchase	Ambiguous, not a verb phrase

Rules:

1. Always noun_verb order, never verb_noun
2. Snake_case only -- no camelCase, no hyphens, no PascalCase
3. Past tense verbs: _started, _completed, _failed, _viewed
4. Specific enough to be unambiguous, not so verbose it is a sentence
5. Prefix with domain when needed: onboarding_step_completed, billing_plan_selected

Standard Event Parameters

Every custom event should include applicable parameters from this table:

Parameter	Type	Example	Required When
user_id	string	usr_abc123	Always (if authenticated)
plan_name	string	professional	Billing/pricing events
value	number	99.00	Revenue events
currency	string	USD	Always with value
content_group	string	onboarding	Page/flow grouping
method	string	google_oauth	Signup/login events
step_name	string	connect_account	Multi-step flows
step_number	number	3	Multi-step flows
source	string	pricing_page	CTA click events

SaaS Event Taxonomy (Reference)

Core Funnel:

visitor_arrived              (automatic page_view in GA4)
signup_started               (user clicked "Sign up")
signup_completed             (account created)
trial_started                (free trial began)
onboarding_step_completed    (params: step_name, step_number)
feature_activated            (params: feature_name)
plan_selected                (params: plan_name, billing_period)
checkout_started             (params: value, currency, plan_name)
checkout_completed           (params: value, currency, transaction_id)
subscription_renewed         (params: value, plan_name)
subscription_cancelled       (params: cancel_reason, plan_name)

Micro-Conversions:

pricing_viewed
demo_requested               (params: source)
form_submitted               (params: form_name, form_location)
content_downloaded           (params: content_name, content_type)
video_started                (params: video_title)
video_completed              (params: video_title, percent_watched)
chat_opened
help_article_viewed          (params: article_name)
invite_sent                  (params: recipient_role)
integration_connected        (params: integration_name)

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GA4 Configuration

Data Stream Setup

1. Create property: GA4 Admin > Properties > Create
2. Add web data stream with your domain
3. Enhanced Measurement -- review each:
   • Page views: Keep enabled
   • Scrolls: Keep enabled
   • Outbound clicks: Keep enabled
   • Site search: Enable if you have search
   • Video engagement: Disable if tracking videos manually (avoids duplicates)
   • File downloads: Disable if tracking via GTM (for better parameters)
4. Configure domains: add all subdomains in your funnel
5. Data retention: Set to 14 months (maximum for free GA4)

Key Events (formerly "Conversions")

GA4 renamed "conversions" to key events in March 2024; "conversions" now refers to key events imported into Google Ads. Mark as key events in GA4 Admin > Data display > Events (star icon):

• signup_completed
• checkout_completed
• demo_requested
• trial_started

Rules:

• Maximum 30 key events per standard property (50 on Analytics 360) -- curate carefully
• Marking a key event is not retroactive -- it affects reports from the time it is marked, not historic data
• Do not mark micro-conversions as key events unless optimizing ad campaigns for them
• Counting method: set to "once per session" for lead events, "every" for purchase events

Source: Mark events as key events (as of September 2026).

Custom Dimensions

Register custom dimensions for any event parameter you want to filter/segment by:

Parameter	Scope	Dimension Name
plan_name	Event	Plan Name
user_id	User	User ID
content_group	Event	Content Group
feature_name	Event	Feature Name

Register in GA4 Admin > Custom definitions > Create custom dimension.

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Google Tag Manager Implementation

Container Architecture

GTM Container
├── Tags
│   ├── GA4 Configuration (All Pages trigger)
│   ├── GA4 Event Tags (one per custom event)
│   ├── Google Ads Conversion Tags (per conversion action)
│   └── Meta Pixel / LinkedIn Insight (if running ads)
├── Triggers
│   ├── All Pages (Page View)
│   ├── DOM Ready
│   ├── Custom Event triggers (one per dataLayer event)
│   └── Element Click triggers (CSS selector based)
└── Variables
    ├── Data Layer Variables (one per dataLayer key)
    ├── Constants (GA4 Measurement ID, etc.)
    └── Lookup Tables (if needed for mapping)

Implementation Pattern: Data Layer Push

Your application pushes events to the data layer. GTM picks them up and sends to GA4.

Application code:

// Push event when user completes signup
window.dataLayer = window.dataLayer || [];
window.dataLayer.push({
  event: 'signup_completed',
  method: 'email',
  user_id: userId,
  plan_name: 'trial'
});

GTM configuration:

Trigger:
  Type: Custom Event
  Event name: signup_completed

Tag:
  Type: GA4 Event
  Event name: signup_completed
  Parameters:
    method:    {{DLV - method}}
    user_id:   {{DLV - user_id}}
    plan_name: {{DLV - plan_name}}

SPA Handling

Single Page Applications need special attention because page views do not fire automatically on route changes.

Option A: History change trigger (GTM built-in)

• Enable "History Change" trigger in GTM
• Fires GA4 page_view on every pushState/popState

Option B: DataLayer push on route change (more control)

// In your router (React Router, Next.js, etc.)
router.events.on('routeChangeComplete', (url) => {
  window.dataLayer.push({
    event: 'page_view',
    page_location: url,
    page_title: document.title
  });
});

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Conversion Tracking: Ad Platforms

Google Ads

Recommended approach: Import GA4 conversions into Google Ads (single source of truth).

1. Link GA4 and Google Ads accounts
2. In Google Ads > Goals > Conversions > Import > Google Analytics
3. Select GA4 key events to import (they become Google Ads conversions)
4. Set attribution model: Data-driven (if 50+ conversions/month), otherwise Last-click
5. Conversion window: 30 days for lead gen, 90 days for high-consideration B2B

Enhanced Conversions: Enable for 15-30% better conversion measurement. Sends hashed first-party data (email, phone) to match conversions that cookies miss.

Meta (Facebook/Instagram)

1. Install Meta Pixel base code via GTM
2. Configure standard events: PageView, Lead, CompleteRegistration, Purchase
3. Conversions API (CAPI): strongly recommended -- client-side pixel loses approximately 30% of conversions due to ad blockers and iOS App Tracking Transparency
4. Deduplication: when using both pixel and CAPI, send the same event_id to prevent double-counting

LinkedIn Insight Tag

1. Install via GTM (Tag type: LinkedIn Insight)
2. Configure conversion events in LinkedIn Campaign Manager
3. Match events to your taxonomy: signup_completed -> LinkedIn "Sign-up" conversion

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UTM Strategy

Convention Enforcement

Parameter	Convention	Example
utm_source	Platform name, lowercase	google, linkedin, newsletter
utm_medium	Traffic type	cpc, email, social, organic
utm_campaign	Campaign identifier	q1-trial-push, brand-awareness-2026
utm_content	Creative variant	hero-cta-blue, sidebar-text-link
utm_term	Paid keyword (search only)	saas-analytics-tool

Critical rules:

• Never tag organic traffic with UTMs (overrides GA4 automatic attribution)
• Never tag direct/internal links with UTMs
• Use a UTM builder spreadsheet or tool -- manual entry causes inconsistency
• Lowercase everything -- Google and google are different sources in GA4

Attribution Windows

Platform	Default	Recommended for SaaS
GA4	30 days	30-90 days (match your sales cycle)
Google Ads	30 days	30 days (trial), 90 days (enterprise)
Meta	7-day click, 1-day view	7-day click only (view-through inflates; 7-/28-day view windows were removed Jan 2026)
LinkedIn	30 days	30 days

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AI Referral Traffic

Visits from AI assistants (ChatGPT, Gemini, Claude, Copilot, Perplexity, etc.) are a growing, distinct acquisition source. Measure them explicitly instead of letting them blur into Referral or Direct.

GA4 "AI Assistant" Channel (as of September 2026)

Since May 13, 2026, GA4's Default Channel Group includes an AI Assistant channel. When the referrer matches Google's list of recognized AI assistants, GA4 sets medium = ai-assistant and campaign = (ai-assistant), and the session is grouped under AI Assistant. No configuration is needed. The rule is evaluated before Referral. Sources: Default channel group, What's new in Google Analytics.

Known Gaps

Gap	What happens	Mitigation
Not retroactive	Sessions before the rollout stay in Referral	Use the custom channel group below for historical comparison
Unrecognized assistants	AI tools not on Google's list still land in Referral	Custom channel group with your own regex
Google AI Overviews / AI Mode clicks	Excluded from AI Assistant; they arrive from google.com and count as Organic Search	Use Search Console (Web search type + Generative AI report) — GA4 cannot isolate them
Referrer stripped	Many app and copy-paste visits arrive with no referrer and fall into Direct	Add UTMs to links you control (e.g., in llms.txt, docs, GPT/app listings); watch Direct landing pages that match AI-cited pages
Assistant-added UTMs	Some assistants append their own UTM (ChatGPT adds utm_source=chatgpt.com to referral links, per OpenAI's publisher FAQ), which changes how source/medium are recorded	Match on session source (which the UTM sets) rather than referrer alone

Fallback: Custom Channel Group

Create a custom channel group in GA4 (Admin > Data display > Channel groups), add an "AI Assistant (custom)" channel above Referral, with the condition Session source matches regex:

^(chatgpt\.com|chat\.openai\.com|openai\.com|perplexity\.ai|www\.perplexity\.ai|gemini\.google\.com|bard\.google\.com|claude\.ai|copilot\.microsoft\.com|edgeservices\.bing\.com|chat\.deepseek\.com|grok\.com|meta\.ai|chat\.mistral\.ai|you\.com|phind\.com)$

Keep the list in version control and review it quarterly; assistant domains change. The campaign-analytics attribution script uses the same list to classify an ai_assistant channel.

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Cross-Domain Tracking

For funnels crossing domains (e.g., acme.com to app.acme.com):

1. GA4 Admin > Data Streams > Configure tag settings > Configure your domains > Add both domains
2. GTM: GA4 Configuration tag > Fields to Set > linker > Add domains
3. Admin > Data Streams > List unwanted referrals > Add both domains

Verification: Visit domain A, click link to domain B, check GA4 DebugView. The session should NOT restart. If a new session starts, cross-domain tracking is broken.

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Consent Management

Consent Mode v2

Required for EU compliance and for maintaining data quality in consent-heavy markets.

Setting	No Consent Mode	Basic	Advanced
User declines cookies	Zero data	Zero data	Modeled data (GA4 estimates)
Data quality impact	25-40% data loss in EU	25-40% data loss	5-15% data loss
Implementation effort	None	Medium	Medium-High

Recommendation: Implement Advanced Consent Mode v2 via GTM with a CMP (Cookiebot, OneTrust, Usercentrics).

Expected consent rates by region:

• EU/EEA: 60-75%
• UK: 70-80%
• US: 85-95%
• Rest of world: 80-90%

Implementation via GTM

1. Install CMP tag (fires first, before any other tags)
2. Set default consent state:
   - analytics_storage: denied
   - ad_storage: denied
   - ad_user_data: denied
   - ad_personalization: denied
3. CMP updates consent state on user choice
4. GA4 and ad tags respect consent automatically

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Data Quality Auditing

Audit Checklist

Event Quality:

• No duplicate events (check GTM Preview for double-fires)
• All custom events have required parameters
• Event names follow naming convention
• No PII in event parameters (names, emails, phone numbers)
• Enhanced Measurement not duplicating GTM custom events

Configuration Quality:

• Data retention set to 14 months
• Internal traffic filter enabled (office and developer IPs)
• Bot filtering enabled (default in GA4)
• Cross-domain tracking working (if applicable)
• Custom dimensions registered for filtered parameters
• Conversion events marked correctly

Consent Quality:

• Consent Mode v2 implemented (if serving EU users)
• CMP banner appearing on first visit
• Tags respect consent state (no firing before consent)
• Consent state persisting across pages

Common Data Quality Issues

Issue	Symptom	Root Cause	Fix
Inflated page views	2x expected volume	GTM page_view + Enhanced Measurement	Disable Enhanced page_view
Missing conversions	GA4 and Ads numbers differ	Attribution window mismatch	Align windows
(not set) pages	Pages show as "/(not set)"	SPA routing not handled	Implement SPA tracking
Self-referrals	Own domain in referral report	Missing cross-domain config	Add domains to referral exclusion
Direct traffic spike	Paid traffic showing as direct	UTMs missing or stripped	Audit UTM usage
Zero EU data	No traffic from EU markets	Consent blocks all tracking	Implement Advanced Consent Mode

Debugging Workflow

Step 1: Open GTM Preview mode
  - Is the tag firing? Check triggers and conditions
  - Is the data layer populated? Check dataLayer in console

Step 2: Check GA4 DebugView (Admin > DebugView)
  - Is the event appearing? If yes, GTM is working
  - Are parameters populated? Check parameter values

Step 3: Check GA4 Realtime report
  - Events appearing with 5-minute delay? Normal
  - Events not appearing at all? Check measurement ID

Step 4: Check Network tab (DevTools)
  - Filter by "collect" or "analytics"
  - Is the request being sent? Check status code
  - Is the request being blocked? Check ad blockers / consent

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Proactive Triggers

Surface these findings without being asked:

• Events firing on every page load with identical parameters: misconfigured trigger causing data inflation
• No user_id parameter on authenticated events: cannot connect analytics to CRM or understand cohorts
• GA4 conversion count differs from Google Ads by more than 15%: attribution window or deduplication issue
• No consent mode in EU markets: legal exposure and 25-40% data underreporting
• All pages showing as /(not set): SPA routing not handled properly
• utm_source showing as direct for known paid campaigns: UTMs missing or being stripped by redirects

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Related Skills

Skill	Use When
campaign-analytics	Analyzing marketing performance and channel ROI (not implementation)
ab-test-setup	Designing experiments (this skill's events feed A/B tests)
launch-strategy	Tracking events for product launches
email-sequence	Setting up email click tracking and UTM parameters

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Troubleshooting

Symptom	Likely Cause	Resolution
GA4 shows 50% less traffic than expected after privacy changes	Client-side tracking blocked by ad blockers and ITP/ETP cookie expiry	Implement server-side GTM tagging — recovers 20-40% of lost attribution data within first quarter
Conversion counts differ between GA4 and Google Ads by >15%	Attribution window mismatch or deduplication failure between pixel and CAPI	Align attribution windows across platforms and ensure matching event_id for deduplication
Events fire in GTM Preview but do not appear in GA4 reports	Measurement ID mismatch, consent mode blocking, or data processing delay	Check Measurement ID in GA4 Configuration tag, verify consent state, wait 24-48 hours for standard reports
UTM parameters show as (not set) in GA4	UTMs stripped by redirects, social platform link wrappers, or internal links overwriting	Audit redirect chains, use UTM-safe shorteners, never tag internal links with UTMs
Server-side container returns 400 errors	Malformed event payload or missing required fields in Measurement Protocol requests	Validate payload against GA4 Measurement Protocol schema, check required client_id and api_secret
Enhanced Measurement duplicating custom GTM events	Both Enhanced Measurement and GTM firing the same event type (e.g., page_view, scroll)	Disable the overlapping Enhanced Measurement toggle for events you track via GTM
Consent Mode v2 reporting zero EU data instead of modeled data	Default consent state not set before GA4 tag fires, or CMP not updating consent correctly	Ensure consent defaults fire as the very first tag in GTM before all other tags

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Success Criteria

• All custom events follow consistent noun_verb snake_case naming convention with zero violations in schema audit
• GA4 conversion counts match ad platform conversion counts within 10% variance
• Server-side tracking recovers 20%+ of previously lost attribution data within 90 days of deployment
• UTM parameter validation passes 100% on all active campaigns (no mixed case, no spaces, no missing required params)
• Consent Mode v2 limits EU data loss to under 15% via behavioral modeling
• Event parameters contain zero PII violations as verified by automated schema checker
• Data retention set to 14 months, internal traffic filtered, and cross-domain tracking verified

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Scope & Limitations

In Scope: GA4 configuration, GTM implementation, event taxonomy design, conversion tracking setup, UTM strategy, consent management, data quality auditing, server-side tagging architecture, cross-domain tracking, ad platform conversion integration (Google Ads, Meta, LinkedIn).

Out of Scope: Product analytics platforms (Amplitude, Mixpanel), data warehouse configuration, custom ETL pipelines, mobile app tracking (Firebase), marketing attribution modeling (see marketing-analyst skill), A/B test statistical analysis (see ab-test-setup skill).

Limitations: Server-side tracking requires a cloud-hosted GTM container (GCP, AWS, or third-party) with associated infrastructure costs. Privacy-first analytics with Consent Mode v2 produces modeled data for non-consented users — modeled data has 5-15% variance from actual. This skill does not make LLM or API calls; all validation is deterministic.

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Scripts

Script	Purpose	Usage
scripts/utm_validator.py	Validate UTM parameters for consistency and naming conventions	python scripts/utm_validator.py urls.csv --json
scripts/event_schema_checker.py	Validate event names and parameters against taxonomy, detect PII	python scripts/event_schema_checker.py events.json --json
scripts/funnel_drop_off_analyzer.py	Analyze conversion funnels and identify biggest drop-off points	python scripts/funnel_drop_off_analyzer.py --stages "Visitors:10000,Signups:1200,Paid:120"