In probability distribution chapter, the numerator of z statistic formula is x - xbar. But in hypothesis testing chapter the numerator is xbar - x. Why is this so?
Anyone?
Your assessment of the calculation in hypothesis testing is incorrect.
It’s not
xbar – x
It’s
sample mean − hypothesized mean
Thanks. But why did the mean change places ? Or are both the formulas unrelated?
It didn’t change places.
In both cases we’re subtracting a mean value from a statistic:
- In the probability section, the statistic is a random value from a distribution, and the mean value is the mean of that distribution.
- In the hypothesis testing section, the statistic is the mean value of a sample, and the mean value is the hypothesized mean value for the distribution from which that sample was taken.
Ah. Got it. Thanks a lot.
You’re quite welcome.