Show that for ANY data set, the sum of the positive deviations from the eman must be exactly equal to the sum of negative deviations from the mean?
I can work this out when subbing in values, but can anyone prove it with formulae?
I presume that by "deviation from the mean" you mean simply the value minus the mean.: . Mean itself is defined by so the sum of deviations is . But is a constant so . Putting those together, . Since that sum is 0, the negative values and positive values must cancel.