得失球差
Goal difference has often replaced the older goal average, or goal ratio. Goal average means the number of goals scored divided by the number of goals conceded. It was replaced by goal difference, which was thought to encourage more attacking play, encouraging teams to score more goals (or points) as opposed to defending against conceding. However goal average is still used as the tiebreaker in Australian rules football where it is referred to as "percentage". This is calculated as points scored divided by points conceded, and then multiplied by 100.