Why are units on Mason\'s SD formula wrong?
If you look at his formula:
- the average (U) is in $/hr (assuming $ is your monetary measure and hours is your time measurement)
- N is unitless
- X is in dollars
- T is hours
Therefore, simple unit analysis of the formula shows that variance has units of $^2 / hrs, and therefore SD would have units of $ / sqrt(hrs).
We measure our average in terms of $/hr so logically the SD would have the same units, why is this not so? Has to be a reason.
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