1.平均數
2.中數
To calculate the median of n numbers，first order the numbers from least to greatest;if n is odd，the median is defined as the middle number，while if n is even，the median is defined as the average of the two middle numbers. For the data 6, 4, 7, 10, 4, the numbers, in order, are 4, 4, 6, 7, 10, and the median is 6, the middle number. For the numbers 4, 6, 6, 8, 9, 12, the median is /2 = 7. Note that the mean of these numbers is 7.5.
3.衆數：一組數中的`衆數是指出現頻率最高的數。
例：the mode of 7，9，6，7，2，1 is 7。
4.值域：表明數的分佈的量，其被定義爲最大值減最小值的差。
例：the range of1，7，27，27，36 is 36-= 37。
5.標準方差：
One of the most common measures of dispersion is the standard deviation. Generally speaking, the greater the data are spread away from the mean, the greater the standard deviation. The standard deviation of n numbers can be calculated as follows:
find the arithmetic mean ;
find the differences between the mean and each of the n numbers ;
square each of the differences ;