Question

what is the empirical formula
in math

Answer 1

Is the empirical formula, 3 median = mode + 2 mean, wrong?

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9 ANSWERS



Terry Moore, PhD in statistics

Answered Jul 22 2016

"Empirical" means "observed". If something has been observed to happen, how can it be wrong? On the other hand, it hasn't been observed in every case. It is an approximation and not meant to be exact. In fact your example is a demonstartion that it works quite well (6.5 is close to 7). The empirical formula originally discovered by Karl Pearson (mean - mode) = 3(mean - median) tends to work when the skewness is small. In fact it can be shown to be approximately true under certain conditions. It can be proved using Edgeworth's expansion (which is an approximate formula for the distribution in terms of the mean and standard deviation and similar quantities).