For a given set of data, spread is often calculated either as the standard deviation or as the IQR (inter-quartile range).
standard deviation is normalised (z-scores, etc.) and so can be used to compare the spread from two different populations, this is not the case with the IQR since the samples from two different populations could have values at two quite different scales,
e.g. Pop A: 100, 67, 89, 75, 120, ... Pop B: 19, 22, 43, 8, 12, ...
What I'm after is a robust (non-parametric) measure that I can use to compare the variation within different populations.
IQR / Median -- this would be by analogy to the coefficient of variation, i.e. to $
Range / IQR
Question: Which is the more meaningful measure for comparing variation between populations? And if it is Choice 1, is Choice 2 useful for anything / meaningful, or is it a fundamentally flawed measure?