Examples of using Sample variance in English and their translations into Thai
{-}
-
Colloquial
-
Ecclesiastic
-
Ecclesiastic
-
Computer
Sample variance.
So this is sample variance.
Sample variance.
Now what is my sample variance?
So our sample variance is-- well, I will just say 0.246.
So I could say-- And this is actually a sample variance.
All of the sample variance distances, right?
Let's get the calculator out to actually figure out our sample variance.
So my variance, my sample variance, is equal to 0.2475.
Actually this is what some people often refer to when they talk about sample variance.
So your sample variance, when you do it this way, might turn out a little bit low.
My sample standard deviation is just going to be the square root of my sample variance.
Now let's also figure out our sample variance because we can use it later for building our confidence interval.
Now given this sample here, what is my sample mean and my sample variance?
And then this sample variance calculated this way will actually underestimate the actual population variance, right?
Plus my sample standard deviation for the control squared, which is the sample variance.
Sample variance is going to be equal to the sum of my squared distances to the mean divided by my samples minus 1.
This is-- So we might just say, well maybe a good way to take the sample variance is do it the same way.
It is equal to-- it is our sample variance-- I will write it over here-- our sample variance is equal to 0.246.
So this is going to be our sample standard deviation one squared, which is the sample variance for that distribution, over 100.
Remember, this is a sample variance, and we want to get the best estimator of the real variance of this distribution.
So then we would have gotten the variance-- we would have gotten the sample variance 9.7 if you divided by n minus 1 instead of n.
Or actually, let's figure out-- we said if this was a sample, if those numbers were sample and not the population, that we figured out that the sample variance was 9.7.
There's several ways, when people talk about the sample variance, there's several tools in their toolkits, there's several ways to calculate it.
Our sample variance here-- so let me draw a sample variance-- we're going to take the weighted sum of the square differences from the mean and divide by this minus 1.
And what it allows us to do is give us an intuition as to why we divide by n-1 when we calculate our sample variance and why that gives us an unbiased estimate of population variance. .
And the hopefully build the intuition on why we divide by n-1 if we want to have an unbiased estimate of the population variance when we're calculating the sample variance.
And then if I wanted to figure out the sample variance using this formula, I would say OK this distance squared plus this distance squared plus this distance squared plus that distance squared and average them all out.
Here's a simulations created by Khan Academy user Justin Helps that once again tries to give us an understanding of why we divide by n-1 to get an unbiased estimate of population variance when we're trying to calculate the sample variance.
Our unbiased sample variance, which is equal to and this is what we see, what we saw in the last several videos, what you see in statistics books and it's confusing why and hopefully Peter's simulation gives you a good idea of why, at least convinces you that this is the case.