Ranking is the process of positioning items such as individuals, groups or businesses on an ordinal scale in relation to others. A list arranged in this way is said to be in rank order.
A ranking can be obtained by evaluating each item in the collection in such a way that any two items can then be compared to see which should come higher in the ranking. In mathematical terms, this is known as a weak order or total preorder of objects. It is not necessarily a total order of objects because two different objects can have the same ranking. The rankings themselves are totally ordered. For example, materials are totally preordered by hardness, while degrees of hardness are totally ordered.
By reducing detailed measures to a sequence of ordinal numbers, rankings make it possible to evaluate complex information according to certain criteria. Thus, for example, an Internet search engine may rank the pages it finds according to an evaluation of their relevance, making it possible for the user quickly to select the pages they are likely to want to see.
Ranking is a technique commonly used in non-parametric statistics.
Strategies for assigning rankings
It is not always possible to assign rankings uniquely. For example, in a race or competition two (or more) entrants might tie for a place in the ranking. When computing an ordinal measurement, two (or more) of the quantities being ranked might measure equal. In these cases, one of the strategies shown below for assigning the rankings may be adopted.
A common short-hand way to distinguish these ranking strategies is by the ranking numbers that would be produced for four items, with the first item ranked ahead of the second and third (which compare equal) which are both ranked ahead of the fourth. These names are also shown below.
Examples of ranking
* In many sports, individuals or teams are given rankings, generally by the sport's governing body
- In football (soccer), national teams are ranked in the FIFA World Rankings and, unofficially, in the World Football Elo Ratings.
- In snooker, players are ranked using the Snooker world rankings
- In ice hockey, national teams are ranked in the IIHF World Ranking
- In golf, the top male golfers are ranked using the Official World Golf Rankings
* In relation to credit standing, the ranking of a security refers to where that particular security would stand in a wind up of the issuing company. For instance, capital notes are subordinated securities; they would rank behind senior debt in a wind up. In other words the holders of senior debt would be paid out before subordinated debt holders received any funds.
* Some sites propose the user to rank whatever exists (what's the best restaurant, the best city, the most popular dog, the top scorer in international air-guitar, ...), like Rankingfever, the most well-known in Europe, or Rankrz
* Search engines rank web pages depending on their relevance to a user's query. See HITS algorithm, PageRank, TrustRank.
* In video gaming, players may be given a ranking. To "rank up" is to achieve a higher ranking relative to other players, especially with strategies that do not depend on the player's skill.
* A bibliogram ranks common noun phrases in a piece of text.
Source of information is wikipedia