I’m trying to compare the variability within two samples which are quite different in scale (pupil capacity of different types of educational establishment (nursery, primary and secondary schools). My approach is to calculate the standard deviation for each sample, then divide that by the sample mean.

I’ve not seen this metric used, so I’m wondering is there an accepted name for it? Or is there is a better metric to use which would explain why I haven’t seen it?

**Answer**

Standard deviation divided by mean is called coefficient of variation. It is defined exactly as you did

$$ c_{\rm v} = \frac{\sigma}{\mu} $$

in terms of population mean and standard deviation, or it can be estimated using sample mean and sample standard deviation.

**Attribution***Source : Link , Question Author : Jamie Bull , Answer Author : Tim*