Google Analytics Audit Test #

137

Uniqueness of Client Id

Why It Matters:

Critical to the basic function of Google Analytics.

Industries:

All

Checks For:

Accuracy

How accurate is your recent data?

Insight Category:

Behavior

Can you tell what visitors are doing?

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Background

A GA4 audit is essential for uncovering missing insights—key data points that organizations don't yet know and can act upon. A well-done audit evaluates both behavioral tracking and traffic attribution, ensuring each is accurate and useful. It also assesses whether the data collected truly supports business decisions and reporting.

Test Detail

This test checks the uniqueness and consistency of the Google Analytics Client ID (client_id), which is the anonymous identifier Google Analytics assigns to users per device/browser. It plays a crucial role in:

  • Session stitching
  • User-level analysis
  • Attribution
  • Audience creation
  • Conversion tracking and deduplication

If client_id values are duplicated across different users or recycled too frequently, you may see:

  • Inflated user counts
  • Inaccurate session attribution
  • Misrepresented conversion paths
  • Broken retargeting or funnel logic

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Google Analytics audit test results.

How to Conduct This Test

Basic Tests

  • In BigQuery, analyze how many unique users are tied to a given client_id:
    SELECT user_pseudo_id, COUNT(DISTINCT session_id) AS sessions
    FROM `your_dataset.events_*`
    GROUP BY user_pseudo_id
  • Look for any user_pseudo_id values that appear to:
    • Be reused across unrelated devices or traffic sources
    • Accumulate extremely high session counts in short timeframes (indicative of bots or implementation errors)
  • In your Google Analytics DebugView, verify that client_id stays consistent during a session and between repeat visits (as expected)
  • Ensure that server-side implementations are not assigning a shared or static client ID to multiple users

Automated, Free Audit

Want to automate detection of Client ID issues? Run our Instant Audit

Or hire a pro to check for uniqueness violations and identity integrity.

How To Fix

  • Ensure Google Analytics or Google Tag Manager is not overriding the client ID manually
  • If using server-side tagging, confirm that:
    • client_id is captured from the correct incoming request
    • It is passed back in the correct context per user
    • It is not hardcoded or statically assigned
  • Avoid overwriting client_id values with internal user IDs or CRM identifiers
  • Consider combining client_id with user_id for stronger user stitching, especially in logged-in environments
  • Validate using both DebugView and live data in BigQuery after making changes
  • Hire a pro to review your tagging and identity setup—so your Google Analytics user data remains trustworthy and accurate.

Tips from a Google Analytics Consultant

Focus on Insights

Every Google Analytics audit should result in a plan for more insights.

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An insight is:

  • something you don't know
  • and can act on to improve performance

The Goal

Identify and remove insight blockers. Don't get tempted to track things you can't act on!

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