00:01
We need to find the critical value, z alpha over 2, but corresponds to the given confidence level.
00:07
So if your confidence level is 97%, that's 0 .97.
00:14
Here we're looking at a two -tailed test.
00:17
I know that because it's alpha over 2.
00:19
So what this is describing is the normal distribution.
00:24
So you have some mean, and the true mean is going to lie somewhere in this is.
00:32
Distribution connected to it.
00:35
And you want to be 97 % confident, but you've got it correct.
00:40
So that means you mark off 97 % of this, this middle bit.
00:46
So this is 97%, and you only exclude the extremes.
00:52
So you're excluding 3%, which means alpha here is 0 .03.
00:59
But because it's alpha over 2, that means it's two -tailed.
01:03
So you're saying you want to exclude both sides...