Science and engineering in Manchester chemist visited Manchester in the 1840s. In his research in Manchester, Smith discovered the existence of acid rain, a by product of the industrial revolution. Smith consequently pushed for greater environmental awareness and helped to found the Noxious Vapours Abatement Society in Manchester, which raised awareness of the consequences of poor air. Joseph Whitworth was an engineer and inventor who hailed from Stockport, Cheshire (now Greater Manchester). A talented mechanic amongst various other engineering roles, for long periods of his life, he worked in factories in Manchester. Whitworth would ultimately devise a standard screw thread system, the first of its
Precision and recall refers to a uniform distribution over the appropriate pool of documents; i.e. by "randomly selected retrieved document", we mean selecting a document from the set of retrieved documents in a random fashion. The random selection should be such that all documents in the set are equally likely to be selected. Note that, in a typical classification system, the probability that a retrieved document is relevant depends on the document. The above interpretation extends to that scenario also (needs explanation). Another interpretation for precision and recall is as follows. Precision is the average probability of relevant retrieval. Recall is the average