Equations for the Number of Matches Required for Stable Performance Profiles

Performance indicators in sport are ofte n specific to individual perform ances rather than being typical for perform ers. Therefore, H ughes et al. (2004b) developed the concept of nor mative profiles of sports perform ance and a m eans of determining the number of m atches required for perform ance indicators to stabilise within a tolerable percentage error of the typical mean for the performer. This technique does not address the possi bility of sa mpling error and involves more calculation than is often necessary to determine the number of matches that are required to produce a stable perform ance profile. This paper develops an equation that can determ ine the number of m atches required for the m ean of a performance indicator to stabilise. Wh ere the performance indicator is normally distributed and the coefficient of variation is 5% or less, the equation determ ines a number of matches required for stability with 95% confidence. The equation was tested and validated during a computerised simulation exercise that generated multiple samples of synthetic data.