00:01
So we're given data for five subject stores, and we have our x1 system before data, and the x2s are the after data, and then we would calculate our xd, which is the difference between x1 and x2.
00:23
So here we want to test at alpha is 0 .05.
00:37
Whether there is a difference, no, whether the data have improved.
00:47
So we want the mean difference to be greater than zero, no less than zero.
00:59
Anyway, our null hypothesis is that there is no difference, and if the data improve, then our sales would grow.
01:10
So that means that the mean for two would be greater than the mean for one, so then the mean one minus mean two, which is our mean difference, would be less than zero, because you're subtracting the larger from the smaller.
01:25
So our alternative hypothesis then is that the mean difference is less than zero, and we're using paired difference here because we're looking at before and after data of the same stores.
01:43
So for part a, we're doing paired difference, and what is the level of significance? level of significance is our alpha, which is 0 .05, and then i already listed the null and alternative hypothesis, and if we're looking for the mean difference to be less than zero in the alternative, then the null hypothesis is that it's equal to or greater than zero...