standard deviation
词源说明
Coined by English mathematician, biometrician, and eugenicist Karl Pearson in 1894 in his paper "On the dissection of asymmetrical frequency curves".
释义（英文）
名词 Noun
- (statistics) A measure of how spread out data values are around the mean, defined as the square root of the variance. Represented with the Greek letter σ (sigma).