dispersion[d?‘sp???(?)n][统计][数] 离差
Dispersion is the spreading of people or things over a wide area. (对人群的)驱散; 散布
quartile四分位数[‘kw??ta?l]
number line 数轴
variance 方差
deviation 标准差[di?v?‘e??(?)n]n. 偏差；误差
a variation that deviates from the standard or norm
原文：http://www.cnblogs.com/biopy/p/4814769.html