> The data in your server logs is data that people sent to you on purpose That's not true: people have no idea what is sent and they're not choosing what's sen

> The data in your server logs is data that people sent to you on purpose That's not true: people have no idea what is sent and they're not choosing what's sent (with the exception of some forms.) It's OK to collect display width, or estimate the time on a page even though people didn't send it to you on purpose.