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(list, sample)
- Returns the variance-to-mean ratio of values in a list.
COPY/// @func ds_list_vmr(list, sample)
///
/// @desc Returns the variance-to-mean ratio of values in a list.
/// Computes for a sample or entire population (default).
///
/// @param {list} list list data structure
/// @param {bool} sample true for sample, false for population
///
/// @return {real} variance-to-mean ratio
///
/// GMLscripts.com/license
function ds_list_vmr(list, sample=false)
{
var n = ds_list_size(list);
if (n == 0) return undefined;
var avg = 0;
var sum = 0;
for (var i=0; i<n; i++) avg += ds_list_find_value(list, i);
avg /= n;
for (var i=0; i<n; i++) sum += sqr(ds_list_find_value(list, i) - avg);
return sum / (n - real(sample)) / avg;
}
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