Non-completion of equestrian competition by competitors may occur for a variety of reasons. However, limited work has been conducted to establish the likely factors causing non-completion. Non-completion by a competitor needs to be carefully considered within any overall analysis of competition data. Non-completing competitors within sporting competitions are potential complicating and confounding factors in the analysis of performance data (Whitaker and Hill, in press). Within a population it is important to establish if there are systematic or nonrandom reasons for non completion; or whether non-completion is entirely a random event (Little and Rubin 1987). If systematic or nonrandom effects are occurring in competition they need to be considered carefully in the wider analysis of the whole population. This will include the application of appropriate statistical methods to the data sets. These may include such techniques as Regression Analysis, Approximate Bayesian Bootstrap, Hot Deck Method or Summary of Single Input Method (ibid).