Bounce Rate Illusion

This is a measurement artifact that can occur when A/B testing website speed. "Bounce rate" refers to the percentage of visitors who leave a site after viewing only one page. A faster page sends analytics tracking signals more quickly and reliably. This means that for users who were going to bounce anyway, the faster page is more likely to successfully report that bounce before the user leaves. Paradoxically, this can make the faster group in an A/B test appear to have a slightly higher bounce rate, even though the user experience was better. This "illusion" is simply a result of more accurate tracking.