[10] Numerous studies have sought to figure out why DNF rates vary greatly, even within the same competitive discipline.
For example, a 2009 New York Times analysis of New York City Marathon results concluded that recreational competitors were more likely to finish the race rather than be classified as DNF: "Elite runners seem more inclined to drop out rather than simply complete the race, and runners visiting from abroad seem more inclined to push themselves to the finish line no matter their time.
"[12] Glace et al. (2002) performed ANOVA analysis of finishers as compared to DNFs in an ultramarathon and concluded that they had statistically different nutrition and liquid intake.
[13] Holbrook et al. found physiological differences between finishers and DNFs among horses engaging in long-distance races.
It is not uncommon though that the more races in a season, the better chance another team will DNF, therefore a championship and purse could still be won.