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

2 sigma 来自两个均方，sigma 是均方的符号。

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的统计学概念——准，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.

关键变量是均值的准准的均值。

Let's say 2.79 is the standard deviation.

设2.79是准偏。

And the standard deviation is 0.5.

准偏为 0.5。

Do you know how to calculate the standard deviation ?

你知道如何计算准吗？

What if we got two standard deviations more conscientious?

如果我们得到两个更认真的准呢？

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

表2中数据的计算准为12.14。

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

雷蒙德，你的成绩应该比黛布拉高一个等级。

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

这个人口数据为基础再用准公式，你觉得变量是多少？

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

表 4 比较了基于准和方的百分比。

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

所，你知道 M 代表平均值，M 代表准，但两者都是希腊语。

So it's going to have a smaller standard deviation.

所它的准偏会更小。

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，使我们的表达式的准等于 1。

So we go down another standard deviation in that direction and another standard deviation above the mean.

所我们在那个方向上再下降一个准，在平均值之上再下降一个准。

Now if we're talking about two standard deviations around the mean-- so if we go down another standard deviation.

现在，如果我们谈论均值附近的两个准——那么如果我们再下降一个准。

And if you take its square root for the standard deviation, which is what we do right here, it's 0.49.

如果你用它的平方根来表示准偏，这就是我们在这里所做的， 它是 0. 49。

So we know our sample standard deviation is 1.04.

所我们知道我们的样本准是 1.04。

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

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

The total variation is based on the standard deviation.

总变异基于准。