quartiles() публичный статический Метод

https://en.wikipedia.org/wiki/Quartile There are multiple methods for computing quartiles: - Inclusive - Exclusive
public static quartiles ( array $numbers, string $method = 'exclusive' ) : array
$numbers array
$method string What quartile method to use (optional - default: exclusive)
Результат array [ 0%, Q1, Q2, Q3, 100%, IQR ]
Документация по классу Descriptive
Пример #1
0
 /**
  * Trimean (TM, or Tukey's trimean)
  * A measure of a probability distribution's location defined as
  * a weighted average of the distribution's median and its two quartiles.
  * https://en.wikipedia.org/wiki/Trimean
  *
  *      Q₁ + 2Q₂ + Q₃
  * TM = -------------
  *            4
  *
  * @param  array  $numbers
  * @return number
  */
 public static function trimean(array $numbers)
 {
     $quartiles = Descriptive::quartiles($numbers);
     $Q₁ = $quartiles['Q1'];
     $Q₂ = $quartiles['Q2'];
     $Q₃ = $quartiles['Q3'];
     return ($Q₁ + 2 * $Q₂ + $Q₃) / 4;
 }