Developed by the National Institute of Standards and Technology (NIST), the Engineering Statistics Handbook is a massive resource for applied statistics methods and probability. The online publication covers a wide range of topics, with the intention of helping engineers and other professionals incorporate statistical techniques into their analysis and designs. It was originally aimed at workers...

Statistics at Square One "was one of the best selling statistical text books in the UK," and it has been revised for this online edition. It was written from a medical statistics perspective, and hence many of the examples involve health related topics. Despite this recurring focus, no prior medical knowledge is required and the book can be used by anyone to learn the fundamentals of statistics....

StatPrimer is "an online, public-domain biostatistics instructional manual." Biostatistics, in this case, can be somewhat misleading; the material covers many universal statistics concepts, but applies them to data sets and examples involving biology. Anyone wanting to learn about hypothesis testing, confidence intervals, regression, and several other statistical topics will find this site a...