The 2 sigma comes from two standard deviation, sigma, the symbol for standard deviation.

2 sigma 来自两个方，sigma 是方符号。

Readers have to wait until page 65 before reaching the first serious concept, standard deviation, which feels too late.

读者得等上65页才能接触到第一个严肃统学概念——标，让人感觉进度太慢。

The critical variable was the standard deviation of the means divided by the mean of the standard deviations.

关键变量是值标除以标值。

Let's say 2.79 is the standard deviation.

假设2.79是标偏。

Do you know how to calculate the standard deviation ?

你知道算标吗？

What if we got two standard deviations more conscientious?

果我们得到两个更认真标呢？

So why even talk about the standard deviation?

那么为什么还要谈论标呢？

The calculated standard deviation of the data in Table 2 is 12.14 .

表2中数据算标为12.14。

Raymond, you were the one who scored one standard deviation higher than Debra.

雷蒙德，你成绩应该比黛布拉高一个等级。

Table 4 compares the percentages based on using the standard deviation and the variances.

表 4 比较了基于标和方百分比。

So, you know M for mean,   as for standard deviation but both in Greek.

所以，你知道 M 代表平值，M 代表标，但两者都是希腊语。

So based on the data given for this population, and using the standard deviation formula, what do you think this variable is?

以这个人口数据为基础再用标公式，你觉得变量是多少？

The standard deviation is just the square root of the variance.

标就是方平方根。

So this whole term right here is how many standard deviations we are away from the mean.

因此，这里整个项表示我们距离值有多少个标。

Which basically just rescales the units so that the standard  deviation of our expression will equal one.

这基本上只是重新调整单位，使我们表达式标等于 1。

And we'll talk-- and we'll move into the standard deviation.

我们将讨论——我们将进入标。

But the sigma right here, that is just the standard deviation of the distribution.

但这里西格玛，其实就是分布标。

DUCKWORTH: So, we've not only gotten smarter, we've become two standard deviations smarter than we were 100 years ago.

DUCKWORTH：所以，我们不仅变得更聪明了，而且比 100 年前更聪明了两个标。

Standard deviation squared is just the variance, right?

标平方就是方，对吧？

The total variation is based on the standard deviation.

总变异基于标。