Random Walk

In web-accessibility evaluation, a random walk is a probabilistic sampling method that starts from a seed page (typically the home page) and follows outgoing links according to a probability rule — for example, with probability d follow a uniformly-chosen outgoing link, and with probability 1-d jump back to a previously-visited page. Over many steps the walk produces a subset of pages that can be used as an audit sample. Random walks are attractive for large, dynamic, or uncrawlable sites because they do not require an up-front list of all pages, but they tend to under-sample pages located far from the seed, so accessibility issues concentrated in deep subtrees can be missed. Variants are used by the European Internet Accessibility Observatory and other large-scale accessibility benchmarks.