Today we got an interesting question from one of our clients:

how would you measure scroll depth on an endless page?

In true The Marketing Technologist fashion, we love to share our thoughts.

The problem

With scroll depth measurement you track how far a user scrolls down on a page. The results are often reported for a set percentage of scroll depth, e.g. 25%, 50%, 75% and 100%. The problem with endless pages, or infinite scroll pages, is that there is no end to the page (these are often product listing pages). So the question arises: how do we track scroll depth here?

A possible solution

When my colleague Bart Persoons shared the question, we started discussing options:

• What if we only tracked scroll depth for the height of the page at page load?
• Should we add virtual pageviews to every newly loaded chunk of content and apply scroll depth there?
• Can we track the newly loaded chunks with separate events?

The answer might be in a combination of these answers. Right now, this would be our advice:

1. Track the scroll depth for the height of the initial page load. These events range from 0% to 100%.
2. After an extra piece of content loads, add a percentage of scroll to the 100% of the initial page load, e.g. by tracking a 125% scroll event when a user reaches the end of the new content.

How design impacts measurement

Endless scroll is a good example of how UX impacts measurement, and how measurement can become a challenge. Luckily, there is always a way to get insights. What do you think of our approach? Would you try something else? Feel free to leave a comment, we’re open for suggestions.