Case Study: Why Improving Customer Experience Is the Key to Increasing Conversions

We noticed in user research sessions and session recordings that many customers of this fashion brand don’t check size and availability of a product on the PDP. They notice these only after they review the product and decide to proceed to checkout.

At this point, when they realise that they have to select a size, they are disappointed and frustrated. If the item is out of stock, users also face ego depletion, resulting in cart abandonment.

Hypothesis and Psychological Technique Applied

We believed that the size selector needed to be redesigned to make it easier for users to see the sizes and availability. We would be able to achieve this by switching the size selector to a tiled version instead of the dropdown that the site currently used.


We re-designed the PDP with the following changes:

  • The size is shown in a tiled format, with a darker colour highlighting the selected size.
  • Unavailable sizes are greyed and crossed out.
  • When the customer selects a size, stock messaging (available, low stock, and unavailable) will be displayed below the selector.
  • When a size is out of stock, a message appears with a basic form for the customer to input name and email to get notification when the size is back in stock.
PDP size selector optimisation

Control (L), Variation


From the observed data, we were able to see that the Variation showed a high probability of being better than the Control on mobile and desktop.


Conversion optimisation is not just about increasing sales, but about increasing sales by making the customer experience better. In this case, the revised approach to size selection—where the elements were more visual and clearer—made it easier for customers to add products to cart, which led to more users completing their purchase.

Our Clients