Research by Chao Liu and colleagues from Microsoft Research now provides a mathematical understanding of users' page-leaving behaviors. The scientists collected data from "a popular Web browser plug-in," analyzing page-visit durations for 205,873 different Web pages for which they had captured upwards of 10,000 visits. Suffice it to say: these guys crunched a lot of data (more than 2 billion dwell times).
The researchers discovered that 99% of Web pages have a negative aging effect. In human–computer interaction (HCI) research, it's extremely rare to get this strong a finding, and Liu and colleagues should be credited with discovering a major new insight.
It's clear from the chart that the first 10 seconds of the page visit are critical for users' decision to stay or leave. The probability of leaving is very high during these first few seconds because users are extremely skeptical, having suffered countless poorly designed Web pages in the past. People know that most Web pages are useless, and they behave accordingly to avoid wasting more time than absolutely necessary on bad pages.
If the Web page survives this first — extremely harsh — 10-second judgment, users will look around a bit. However, they're still highly likely to leave during the subsequent 20 seconds of their visit. Only after people have stayed on a page for about 30 seconds does the curve become relatively flat. People continue to leave every second, but at a much slower rate than during the first 30 seconds.
So, if you can convince users to stay on your page for half a minute, there's a fair chance that they'll stay much longer — often 2 minutes or more, which is an eternity on the Web.
So, roughly speaking, there are two cases here:
bad pages, which get the chop in a few seconds; and
good pages, which might be allocated a few minutes.
Note: "good" vs. "bad" is a decision that each individual user makes within those first few seconds of arriving. The design implications are clear:
To gain several minutes of user attention, you must clearly communicate your value proposition within 10 seconds.