It's the sampling distribution of the sample mean.

它是样本均值的抽样分布。

So the mean of the sampling distribution of the sample mean, we'll write it like that.

所以样本均值的抽样分布的均值，我们会这样写。

So as that approaches infinity, your actual sampling distribution of the sample mean will approach a normal distribution.

因此，当它接近无穷大时，样本均值的实际抽样分布将接近正态分布。

The sampling distribution of the sample mean.

样本均值的抽样分布。

So the sampling distribution of the sample mean-- let me write it over here.

所以样本均值的抽样分布——让我在这里写下来。

Where it's equivalent to taking a sample from the sampling distribution.

它相当于从抽样分布中抽取样本。

So when we get our sample mean we are sampling from the sampling distribution of the sampling mean.

所以当我们得到我们的样本均值时，我们是从抽样均值的抽样分布中抽样。

All of these things I just mentioned, these all just mean the standard deviation of the sampling distribution of the sample mean.

我刚才提到的所有这些东西，这些都只是意味着样本均值的抽样分布的标准偏差。

Now, to show that this is the variance of our sampling distribution of our sample mean, we'll write it right here.

现在，为了表明这是样本均值的抽样分布的方差， 我们将把它写在这里。

So here, when n is 20, the standard deviation of the sampling distribution of the sample mean is going to be 1.

所以在这里，当 n 为 20 时，样本均值的抽样分布的标准差将为 1。

We don't know the true mean of the sampling distribution, and we also don't know the true standard deviation of the sampling distribution.

我们不知道抽样分布的真实均值，也不知道抽样分布的真实标准差。

So this is the sampling distribution.

这就是抽样分布。

But what's neat about this is that the sampling distribution of the sample mean, so you take 50 people, find their mean, plot the frequency.

但这很巧妙的是样本均值的抽样分布，所以你拿 50 个人， 找到他们的均值， 绘制频率。

So the probability that p is within two standard deviations of the sampling distribution of x is 95.4%.

所以 p 在 x 的抽样分布的两个标准差范围内的概率是 95.4%。

Our best estimate of the standard deviation of the sampling distribution of the sample mean is 0.05.

我们对样本均值的抽样分布的标准差的最佳估计是 0.05。

This, right here-- if we can just get our notation right-- this is the mean of the sampling distribution of the sampling mean.

这个，就在这里——如果我们的符号正确的话——这就是抽样均值的抽样分布的均值。

It is a sample from the sampling distribution of the sample mean.

它是来自样本均值的抽样分布的样本。

So the mean of the sampling distribution of the sample proportion.

所以样本比例的抽样分布的均值。

And just to visualize it properly, let me draw the sampling distribution for the sample proportions.

为了正确地形象化它，让我画出样本比例的抽样分布。

But we're going to think about the sampling distribution for the difference of this sample proportion and this sample proportion.

但是我们要考虑这个样本比例和这个样本比例之差的抽样分布。