The statistics of web performance

Analysis of user experience is typically done by taking a random sample of users, measuring their experiences and extracting a single number from that sample. In terms of web performance, the experience we need to measure is user perceived page load time, and the single number we need to extract depends on the distribution of measurements across the sample.

There are a few contenders for what the magic number should be. Do you use the mean, median, mode, or something else? How do you determine the correctness of this number or whether your sample size is large enough? Is one number sufficient?

This talk covers some of the statistics behind figuring out which numbers one should be looking at and how to go about extracting it from the sample.