7% 77% is class average and the standard deviation was 17% so you can see where things lie. 50% is a pass.

7是平均水平，标准偏差是%,这就是事情所在，50%就及格。

麻省理工公开课 - 固态化学导论课程节选

Bullish sentiment is just slightly above one standard deviation from the historical average and bearish sentiment is within one standard deviation.

FORBES: Why Is Bullish Sentiment Near Two And A Half Year High?

Placing asset categories on the efficient frontier requires knowing their historical average return and standard deviation.

FORBES: Asset Allocation and the Efficient Frontier

Once you know the average return, the standard deviation of each index and the correlation coefficient between each pair of indexes, the rest is math.

FORBES: Asset Allocation and the Efficient Frontier