In cricket, one measure of a batsman's worth is the number of runs the player scores per innings, which is known as the player's average. Calculating this statistic is straightforward for any batsman who's obligingly and unfailingly managed to be dismissed prior to the completion of their team's innings as then it's just a simple division of total runs scored by number of innings batted, but it's problematic as soon as a batsmen has registered a "not out".