Google Analytics Audit Test #

18

(not set) Item at `add_to_cart`

Why It Matters:

Critical to understanding friction in the shopping process on a product-by-product level.

Industries:

Ecommerce

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 whether add_to_cart events are firing without complete item metadata, such as missing item_id or item_name, which may show as (not set) in reports.

These events indicate someone added a product to their cart, but GA4 doesn’t know which one.

This results in:

  • Incomplete or misleading ecommerce reports
  • Inability to analyze which products are added to cart most
  • Broken funnel or product-level conversion tracking
  • Lost insights into merchandising, pricing, or category performance

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How to Conduct This Test

Basic Tests

  • In GA4 > Explore, create a Free-form report:
    • Dimensions: Item name, Item ID
    • Metrics: Add-to-cart events
    • Filter for where Item name = (not set) or Item ID = (not set)
  • In GA4 > Reports > Monetization > Ecommerce Purchases, look for any “(not set)” values in the product dimension columns

Advanced QA

  • In BigQuery, run the below query:
    SELECT ep.key, ep.value.string_value, COUNT(*) AS event_count
    FROM `your_dataset.events_*`,
         UNNEST(event_params) AS ep
    WHERE event_name = 'add_to_cart'
      AND (ep.key = 'item_name' OR ep.key = 'item_id')
      AND (ep.value.string_value IS NULL OR ep.value.string_value = '(not set)')
    GROUP BY ep.key, ep.value.string_value;
  • If you're seeing a large number of add_to_cart events without valid item identifiers, your ecommerce tracking is compromised.

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How To Fix

Fixing 'add_to_cart' events with (not set) items

  • Use the recommended push to the dataLayer, ensuring the items array is complete:
    gtag('event', 'add_to_cart', {
      currency: 'USD',
      value: 39.99,
      items: [{
        item_id: 'SKU_12345',
        item_name: 'Leather Wallet',
        quantity: 1
      }]
    });
  • In Google Tag Manager, confirm that:
    • The product data layer includes item metadata on the “Add to Cart” interaction
    • The GA4 event tag correctly maps to items and does not fire with empty or null fields

QA Tips

  • QA the event using GA4 DebugView and confirm that:
    • add_to_cart fires only once per click
    • It includes a properly structured items array with no missing fields
    • Hire a pro to troubleshoot and complete your ecommerce event tracking so every cart action provides insight—not confusion.

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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