Medical testing to determine if a patient has certain disease or not – the classification property is the presence of the disease. A "pass or fail" test method or quality control in factories, i.e. deciding if a specification has or has not been met – a go/no go classification. Information retrieval, namely deciding whether a page or an article should be in the result set of a search or not – the classification property is the relevance of the article, or the usefulness to the user.