Imagine running an A/B test where 100,000 users see your new design … or do they?

Are your A/B Tests telling the truth?

Many A/B tests count impressions/views/sessions on page load regardless of whether the user scrolls to that change or not.

This can lead to:  

Misleading or over inflated data – Counting users who never actually saw the change. Slower decision-making – Making choices based on incomplete data. Longer time to reach statistical significance – Delaying test conclusions.

Recommended Approach

Here at Fabric Analytics, we recommend view-based tracking which ensures that only the users who could’ve been influenced by the test are counted.

By doing this, you:

Improve data accuracy – You’re measuring real engagement, not just visits. Make better decisions – More reliable data leads to more confident optimisations. Potentially get faster results – Less overinflated data may help reach statistical significance sooner.

We implement view-based tracking manually in to each test using the JavaScript Intersection Observer API, which will detect when an element enters the viewport and then fire the tracking.

Example code:

// This function logs a tracking event when an element is in view
function fireTrackingEvent(elementId, variant) {
 console.log(`Element ${elementId} is in view. Firing tracking event for variant: ${variant}`);
}

// Create a new IntersectionObserver instance
const observer = new IntersectionObserver((entries, observer) => {
 entries.forEach(entry => {
   // Check if the element is intersecting (in view)
   if (entry.isIntersecting) {
     const element = entry.target;
     const elementId = element.getAttribute('id');
     const variant = element.getAttribute('data-variant');
     fireTrackingEvent(elementId, variant); // Fire a tracking event
     observer.unobserve(element);
   }
 });
}, {
 // Trigger the callback when 50% of the element is in view
 threshold: 0.5
});

// Select all elements with the class 'element' and observe them
document.querySelectorAll('.element').forEach(element => {
 observer.observe(element);
});

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Better Tracking = Better Results

If you are using A/B testing in your field of work or know colleagues that do, I would highly recommend implementing view-based tracking as an additional event. You’ll soon find out how much that extra noise has been impacting your results.  

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