00:01
So we're looking at the t distribution table and deciding what critical values to use.
00:06
And we have the not equal to, so i'll draw a little picture of the distribution like this.
00:14
And we know we're splitting the area of this .01 into the two tails.
00:19
So we'll have .005 in the lower tail and .005 in the upper tail.
00:25
And we want to have the degrees of freedom with the variances being assumed to be equal.
00:32
So the degrees of freedom is the sum of the two less two.
00:37
So that's 20 less two is 18.
00:39
So i need to look up with 18 degrees of freedom these values.
00:43
And so i'll find this first one looking in my tail.
00:46
Again, with 18 degrees of freedom and .005 in that upper tail.
00:53
So the first critical value is 2 .878.
00:57
And the other will be negative 2 .878.
01:01
So those are your critical values if you are pooling and assuming that the standard deviations or variances are equal.
01:09
Now, if we're assuming that they're not equal, then we have a little different scenario.
01:14
We're still going to have two...