众数 (数学)
维基百科，自由的百科全书
众数指一组数据中出现次数最多的数据。用众数代表一组数据，可靠性较差，不过，众数不受极端数据的影响，并且求法简便。在一组数据中，如果个别数据有很大的变动，选择中位数表示这组数据的“集中趋势”就比较适合。
It is especially useful when the values or observations do not have an obvious order (usually when the data are not numeric) since the mean and median may not be well defined. For example, the mode of {apple, apple, banana, orange, orange, orange, peach} is orange.
In a gaussian (i.e. bell curve) distribution, the mode is at the peak. The mode is therefore the value that is most representative of the distribution. For example, if you measure people's height or weight and the values form a bell curve distribution, the peak of this bell curve would be the most common height or weight among these people. The mean/average value can often be influenced by outliers or skews and can be well away from the peak of the distribution and therefore not a value representative of the largest number of people.
In gaussian distributions there is a mathematical relationship between the mean, median and mode known as Karl Pearson's empirical formula for the mode. This formula is that the mode is three times as far from the mean as the median is from the mean in the same direction. For example, the heights of students studying physical education in a school might be distorted by the basketball team. Thus the average might be 6 foot, but the median would be less, at 5 ft 10 inches, and the mode would be at 5 ft 6 inches. Thus a quick check of whether the mean and median have similar values will tell if the distribution is skewed and provides a quick means of determining the value representative of the mode.
