# ds_list_vmr

In probability theory and statistics, the variance-to-mean ratio (VMR), like the coefficient of variation, is a normalized measure of the dispersion of a probability distribution: it is a measure used to quantify whether a set of observed occurrences are clustered or dispersed compared to a standard statistical model.

It is defined as the ratio of the variance $$\sigma^2$$ to the mean $$\mu$$,

$$\large D = {\sigma^2 \over \mu }$$.

ds_list_vmr(id [,sample])
Returns the variance-to-mean ratio of the values in a given list.
COPY/// ds_list_vmr(id [,sample])
//
//  Returns the variance-to-mean ratio of the values in a given list.
//
//      id          list data structure, real
//      sample      true if the list is made up of a sample, bool
//
{
var n, avg, sum, i;
n = ds_list_size(argument0);
avg = 0;
sum = 0;

for (i=0; i<n; i+=1) avg += ds_list_find_value(argument0, i);
avg /= n;
for (i=0; i<n; i+=1) sum += sqr(ds_list_find_value(argument0, i) - avg);

return sum/(n - argument1)/avg;
}


Contributors: Quimp

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