Case Study: How Important Is Filter Functionality in Increasing Conversions?

For a home furnishings client, we saw in Google Analytics that many users who interacted with the filter on the product listings page (PLP) did not reach the product details page (PDP). This was unusual because the filter looked quite easy to use.

When we looked at session recordings, we saw that users actually did not notice the filter as it was not easily visible on the page.

Hypothesis and Psychological Technique Applied

We believed that by improving the functionality of the filter and making it more prominent and visible, visitors would be able to find relevant products more easily and would therefore be more likely to convert.

The following principles supported our hypothesis:

  • What You See Is All There Is (WYSIATI): The tendency to form impressions and judgements based only on the information available to us, overlooking important details that might be absent or not easily visible.
  • The Paradox of Choice: The inability to make decisions when faced with excessive choice, possibly leading to not making a decision at all: such as not buying anything because there are too many options to choose from.


We made the filter button sticky on the page as well as more prominent in visual hierarchy. The Variation highlighted the filter in a contrasting colour on the page.

Filter optimisation

Control | Variation


From the observed data, we were able to see that the Variation showed a high probability of being better than the Control, especially on Mobile. For Desktop and Tablet, though the results were not significant, the Variation did generate higher user conversion rates.

Overall, it worked better for returning users than new users. There was a considerable increase in click-throughs to PDPs and in sessions with the filter being used. Additionally, the user conversion rate was significantly high for visitors who used the filter.


Though the change was a simple one, it improved the number of sessions, click-throughs to PDP, as well as conversion rates for the business. It is not enough to have a functionality that makes customer journey more convenient; it’s important that users are able to see and make use of such a functionality.

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