recursive.php

<?php
function adjust_for_variance($price_array, $variance_threshold) {
  $variance = calculate_variance($price_array);
  if ($variance > $variance_threshold) {
    sort($price_array);
    array_pop($price_array);
    $price_array = adjust_for_variance($price_array, $variance_threshold);
  } else {
    return $price_array;
  }
}

function calculate_variance($price_array) {
  if (is_array($price_array)) {
    return round(((max($price_array) - min($price_array)) / (array_sum($price_array) / count($price_array)) * 100), 3);
  } else {
    return "<span class='nan'></span>";
  }
}