John Maeda tweeted this link to an excellent, intuitive explanation of Standard Deviation by Amar Sagoo. Standard Deviation, Explained Intuitively

Another of my clients is about embark on another round of A/B testing, so I thought I’d post some of my favorite A/B testing resources, summarizing each as a single rule: Why you should always set your sample size (n) in advance: In How Not to Run an A/B Test @evmill makes the case for always fixing your sample size in advance. I generally agree with him – this is good research design.

The best (and least “mathy”) explanation I’ve seen for Confidence Intervals in a long time. Anyone who relies on quantitative research should understand this. What Is a Confidence Interval and Why Would You Want One?