Compare methods

	Competitive Balance Index	Sport Event Economic Impact Analysis
Field	Sport Leisure Studies	Sport Leisure Studies
Family	Process / pipeline	Process / pipeline
Year of origin	2002	1995
Originator	Brad R. Humphreys; P. Dorian Owen, Michael Ryan & Clayton Weatherston	John L. Crompton
Type	Descriptive index pipeline for quantifying parity in sports leagues	Input-output multiplier pipeline for event-attributable spending
Seminal source	Humphreys, B. R. (2002). Alternative measures of competitive balance in sports leagues. Journal of Sports Economics, 3(2), 133-148.	Crompton, J. L. (1995). Economic impact analysis of sports facilities and events: Eleven sources of misapplication. Journal of Sport Management, 9(1), 14-35.
Aliases	Noll-Scully Ratio, League Parity Index, Competitive Balance Ratio, Win-Percentage Dispersion Measures	Event Economic Impact Study, Visitor Spending Multiplier Analysis, Sport Tourism Impact Assessment, Input-Output Event Analysis
Related	3	3
Summary	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.	Sport event economic impact analysis estimates the economic activity a region gains from hosting an event by tracing the new spending that visitors inject and propagating it through the local economy with input-output multipliers. John Crompton's foundational 1995 paper in the Journal of Sport Management is as much a warning as a method: it catalogued eleven recurring sources of misapplication — counting local residents' spending, using sales rather than income multipliers, ignoring time-switchers and casuals, omitting costs and opportunity costs — that systematically inflate headline numbers. His 2006 follow-up was blunter still, framing many impact studies as instruments for political shenanigans designed to justify subsidies rather than to find economic truth. Done correctly, the method isolates genuinely new, event-attributable spending by non-locals, applies an appropriate income multiplier, and nets out the public costs and displacement that boosters routinely ignore.