Airbnb Switched To A Bigger Button After Running This Design Experiment
Here is a perfectly simple optimization of a "Get started" button on Airbnb's host signup landing page. Airbnb ran an experiment of a smaller vs larger button size. I know because I managed to capture two diverse screenshots with the same date stamp. :) More so, a few months later Airbnb rolled out the later button to 100% of their traffic - hinting at a successful experiment outcome.
Highlighted UI Changes From This Leak
The distinct change in this experiment was clearly the increased button size visible in variant B. If you look more closely however, you'll also notice that due to the limited width of the container, the button was also moved to the next line. This slightly extended the height of the container and pushed the content a little further down. Nevertheless I find this as perfect evidence in favor of the Bigger Form & Buttons pattern.