Stable does not mean accurate
Once during a TV commented biathlon event a sportcaster said, comparing two biathletes' shooting, that one of them is a more stable shooter since he has a bigger percent of hits. Of course everyone understood what the sportcaster meant, but strictly speaking accuracy and stability are different things. One biathlete can have 60% of hits in the season, and another one — 80%, but the first one hits 60% of targets in every race, while the second one can hit all targets in two races but fail the third one hitting only 40% of targets. It is evident that the first sportsman is more stable, though he has smaller percentage of hit targets.
Biathlete's shooting stability in figures can be expressed by such a mathematic notion as a mean square deviation. For each race we will calculate the difference between the percentage of sportsman's hits in this race and the percentage of his hits throughout the whole season, and square this difference. The average value of this variable by all races is called a dispersion, and a root mean square — a mean square deviation. The less the mean square deviation is, the more stable is the sportsman.
Following the links below you can view biathletes' shooting stability calculation results. Only the results of those sportsmen who had at least 10 races in the season, were taken into account.
