/**
* Calculates the "Median Absolute Deviation" of an array of data.
*
* Formula:
* 1) Sort the array
* 2) Calculate the first median
* 3) Create new array that each item will be the item of the initial
* array minus the first median, as absolute values
* 4) Calculate the median again
*
* @param array $array_of_values
*/
public static function madCalculate(array $data)
{
$new_data = [];
// Step 1.
sort($data);
// Step 2.
$first_median = Basic::median($data);
// Step 3.
foreach ($data as $val) {
array_push($new_data, abs($val - $first_median));
}
// Step 4.
$mad = Basic::median($new_data);
return $mad * 1.4826;
}