I'm looking for a book to refresh my knowledge of statistics. I did a course in university while studying science 20 years' ago and I have forgotten most of it. I'm now at the stage of standard deviations, modes, means and medians.
The current impetus to relearn stats was triggered by perfomance counter data. I want to build up a baseline in order to determine what 'normal' is, but the more I think I think about it, the more questions I have — mostly about population. How often should I measure? How far back should my data go? Is the mean plus/minus 2 standard deviations enough? What fallacies am I not accounting for?
Can anyone recommend a good, readable introduction to statistics? I'm not scared by maths.
Koen Verbeeck's blog post  on Nathan Yau's book review of Naked Statistics by Charles Wheelan does look good.