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

2 sigma 来自均方差，sigma 是均方差的符号。

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

读者得等65能接触到第一严肃的统计学概念——标准差，让感觉进度太慢。

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

所以它的标准偏差会小。

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

关键变量是均值的标准差除以标准差的均值。

Let's say 2.79 is the standard deviation.

假设2.79是标准偏差。

Do you know how to calculate the standard deviation ?

你知道如何计算标准差吗？

What if we got two standard deviations more conscientious?

如果我们得到认真的标准差呢？

So my sample standard deviation is 0.50.

所以我的样本标准差是0.50。

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

表2中数据的计算标准差为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等级。

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

表 4 比较了基于标准差和方差的百分比。

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

以这口数据为基础再用标准差公式，你觉得变量是多少？

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

所以，你知道 M 代表平均值，M 代表标准差，但者都是希腊语。

My sample standard deviation is just going to be the square root of my sample variance.

我的样本标准差就是样本方差的平方根。

So that could be the standard deviation, or the variance, or the standard deviation, that would be equal to 1.

因此，这可以是标准差、方差或标准差，其值都等于1。

So why even talk about the standard deviation?

那么为什么还要谈论标准差呢？

So that standard deviation is going to be that distance over there.

因此，那标准差就是那边的那距离。

So there's some standard deviation associated with this distribution.

所以这分布有一标准差。

And if I want to figure out my sample standard deviation I just take the square root of that.

而如果我想计算样本标准差，我就取那值的平方根。

And we know that 2 is-- actually it's 2 variances or 2 standard deviations from the mean.

我们知道，2实际是距离均值2方差或2标准差的位置。