This entry in the online encyclopeida, Wikipedia, describes Markov Chains, their properties, discrete state spaces, and formulas for calculating probabilities using Markov Chains. Links to examples and scientific applications are also included.
Gives textbook-like explanation with some real-life data to compute a t-test and determine if two population means are equal. Also has some links for case studies and a web-based program called Dataplot. There is a printer-friendly version on the main homepage (see source).
Gives very detailed explanation of t-tests (confidence intervals, one-sample, two sample independent, two sample paired, pooled and unpooled variances). Discusses the assumptions that are made for each type of t-test. This topic is part of an online textbook.