This expression right here would be a surface, I guess you could view it as a surface in three dimensions, where for any m and b is going to be a point on that surface that represents the squared error for that line.

这个表达式可以看作是一个表面，在三维空间中，对于任率m和截距b，都会在这个表面上有一个点，代表该直线平误。

In the cost function, the squared error for the second example is also 0 squared.

在成本函数中，第二个示例平误也是 0 平。

The fifth column is the F value. This is determined by dividing the mean square for the treatments by the mean square error. It is this value that determines if there are any significant differences between the treatment means.

第五列是F值。这是通过将处理均除以均误来确定。正是这个值决定了处理平均值之间是否存在显。

If the squared error of the line is huge, then that means there's a lot of error between the data points and the line.

如果直线平误很大，那就味数据点与直线之间误很多。

So if we find the m and the b values that satisfy the system of equations, we have minimized the squared error.

所以如果我们找到了满足程组m和b值，我们就最小化了平误。

And we want the squared errors between each of the points of the line.

我们希望得到线上每个点之间平误。

So this is the squared error of the line.

所以这就是这条直线平误。

Our goal is to find the m and the b, which would define an actual line, that minimize the squared error.

我们目标是找到率m和截距b，它们定义了一条实际直线， 使平误最小。

So this whole expression, I'm just going to rewrite it, is the same thing as-- and remember this is just the squared error of the line.

所以这整个表达式，我只是要重写它，是一样——记住这只是直线平误。

You put it into this expression for the squared error of the line.

你把它代入这条线平误表达式中。

This is the squared error of the line axis.

这是直线轴平误。

So are squared error versus our line, our total squared error, we just computed to be 2.74.

所以我们平误相对于这条线，总平误我们刚刚计算出来是2.74。

So once again, this is just the squared error of that line with n points.

所以再一次，这只是那条有 n 个点直线平误。

Sometimes, it's called the squared error.

有时，它被称为平误。

And so you can even visualize it the same way we visualized the squared error from the line.

你可以用同样式来可视化它，就像我们可视化从回归线平误一样。

We have the squared error of the line.

我们有了这条线平误。

If the squared error of the line is really small what does that mean?

如果直线平误真很小，那味什么？

The way that we do that, is we find a point where the partial derivative of the squared error with respect to m is 0, and the partial derivative with respect to b is also equal to 0.

我们实现这一点法是，找到一个点， 使得平误对m偏导数为0， 同时对b偏导数也等于0。

If the squared error of the line is small, it tells us that the line is a good fit.

如果直线平误很小，就说明这条直线拟合得很好。

And so if the squared error of the line is large, this whole thing's going to be close to 1.

如果这条线平误很大，那么整个式子就会接近1。