The original design of Zoro had the categories listed at the very bottom of the page:
The category listings are not very scannable nor were they easy to find. Many of our customers tried to click on the category headers, which lead to frustration because they didn’t link anywhere.
To try and promote the new category pages, help customers understand our wide product selection, and to reduce overall frustration, we decided to run a test.
We had three variations of the category listings: The original, the new buttons with icons, and the new buttons with images. All traffic to the website was split evenly between the three variations.
The test ran for a little under 2 weeks before reaching significance in many measurements.
Both button variations significantly beat the original in transactions, conversion rate, and clicks. The difference between icons and images, however, was never significant. Ultimately we decided that while icons would have been easier to implement in other designs, the images were more meaningful to customers. Simply put, they better described the category and were less ambiguous.