00:01
So i'm going to let d stand for just for convenience, the beginning time minus what the end time is.
00:06
And we could subtract the opposite way as well.
00:09
But it talks about is there a difference? so we would assume that that difference is non -existent, that there is no difference between the beginning and the end so that the mean difference is zero.
00:20
And alternately, that it's different.
00:23
So they didn't say that they wanted to test to see if the time had gotten smaller.
00:28
They just asked if it's different.
00:31
So we have a total of eight people, and we're doing a two -tail test, and we want our significance level to be 1%.
00:42
So we need to split that 1 % between the two tails.
00:46
So this needs to be 0 .005, and this needs to be 0 .005.
00:51
And we'll find that t value with 8 degrees, excuse me, 7 degrees of freedom, that t -star value, with 5%.
00:58
Or 0 .5 % in that upper tail.
01:02
And that corresponds to, with 7 degrees of freedom, looks like that is 3 .499.
01:09
And this one is negative 3 .499.
01:12
So we would reject the null anytime we have our test statistic, which is a t value with 7 degrees of freedom, being less than negative 3 .499.
01:27
Or if that test statistic is greater than 3 .49.
01:32
So we can actually plan all this out before you actually look at the data...