casebash

I'm wanting to learn about A/B testing, but I'd prefer to learn it from a resource that explains the statistical aspect rigorously. Statistics can be a very hard area to get right - if I learn it from a blog post then I can't be certain that what I am learning is correct. Can anyone suggest such a resource?

There are a number of tools for compressing JPEG files. Do some compress better than others? If so, which tends to compress the best?

Are there any alternatives to HipChat? In particular, I'm looking for lightweight chat clients that support both individual and group chats, and that have a simple user interface. It'd also be nice to have a native client for Mac

There are a large number of question and answer sites out there, but very few which provide good answers. The ones I have found that tend to provide good answers are as follows:

StackExchange Network (including StackOverflow) Ask MetaFilter Quora Reddit (on particular sub-reddits such as Ask Science, Ask Historians, Explain Like I'm Five and sometimes Ask Reddit)

Are there any other question and answer sites out there with a high quality of discussion? I'm quite surprised that I haven't been able to find any newer entrants - it's actually easier for new question and answer sites to have a high quality of discussion