Editing Level of measurement (section)

====Central tendency and statistical dispersion====
The [[mode (statistics)|mode]], [[median]], and [[arithmetic mean]] are allowed to measure central tendency of interval variables, while measures of statistical dispersion include [[range (statistics)|range]] and [[standard deviation]]. Since one can only divide by ''differences'', one cannot define measures that require some ratios, such as <!--- the studentized range or. --- Error: studentized range is a ratio of a difference (range) to a root-mean-square difference (standard DEVIATION from the mean ---> the [[coefficient of variation]]. More subtly, while one can define [[Moment (mathematics)|moments]] about the [[Origin (mathematics)|origin]], only central moments are meaningful, since the choice of origin is arbitrary. One can define [[standardized moment]]s, since ratios of differences are meaningful, but one cannot define the coefficient of variation, since the mean is a moment about the origin, unlike the standard deviation, which is (the square root of) a central moment.