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	Competitive Balance Index	Notational Analysis in Sport
分野	Sport Leisure Studies	Sport Leisure Studies
系統	Process / pipeline	Process / pipeline
提唱年	2002	2004
提唱者	Brad R. Humphreys; P. Dorian Owen, Michael Ryan & Clayton Weatherston	Mike Hughes & Ian Franks; Mike Hughes & Roger Bartlett
種類	Descriptive index pipeline for quantifying parity in sports leagues	Observational pipeline for systematic recording of match events
原典	Humphreys, B. R. (2002). Alternative measures of competitive balance in sports leagues. Journal of Sports Economics, 3(2), 133-148.	Hughes, M., & Franks, I. M. (Eds.). (2004). Notational Analysis of Sport: Systems for Better Coaching and Performance in Sport (2nd ed.). London: Routledge. ISBN: 9780415290043
別名	Noll-Scully Ratio, League Parity Index, Competitive Balance Ratio, Win-Percentage Dispersion Measures	Match Analysis, Performance Analysis (Notational), Hand Notation Systems, Tactical Notation
関連	3	3
概要	Competitive balance indices quantify how evenly matched the teams in a sports league are — the parity that the 'uncertainty of outcome' hypothesis says fans value and that economists treat as central to a league's product. The workhorse measure is the Noll-Scully ratio, which compares the actual standard deviation of teams' win percentages to the standard deviation that would arise in an idealized league where every team had equal playing strength, so that a value near one signals balance and large values signal dominance by a few clubs. Brad Humphreys's 2002 paper showed the limits of single-season dispersion measures and proposed the Competitive Balance Ratio to capture how standings change over time, while Owen, Ryan, and Weatherston's 2007 work adapted the Herfindahl-Hirschman index of concentration to wins, correcting it for the number of teams. Together these give a toolkit of dispersion and concentration indices for measuring league parity.	Notational analysis is the systematic recording of the discrete events that make up a sporting performance, so that what happened on the field can be turned into objective, quantifiable evidence rather than the fallible recollection of coaches. Mike Hughes and Ian Franks, in their 2004 edited volume Notational Analysis of Sport, codified the discipline: define a coding system of actions, locations, and outcomes; tally events from video or live observation; and derive summary indicators that describe and discriminate performance. Hughes and Bartlett's 2002 paper on performance indicators added the crucial idea that raw counts must be turned into meaningful, normalized indices — and validated against the criterion of distinguishing successful from unsuccessful play — before they can guide coaching. Together these works ground a pipeline that runs from a structured observation scheme through reliable notation to interpretable performance profiles.