stats_kurtosis

// If you don't have the php_stats library, you can use this function:
public static function getKurtosis( $values )
{
 $numValues = count( $values );
 if ( $numValues == 0 ) {
 return 0.0;
 }
 
 // Use function from php_stats library if available
 if ( function_exists( 'stats_kurtosis' ) ) {
 return stats_kurtosis( $values );
 }
 
 $mean = array_sum( $values ) / floatval( $numValues );
 $add2 = 0.0;
 $add4 = 0.0;
 
 foreach ( $values as $value ) {
 if ( ! is_numeric( $value ) ) {
 return false;
 }
 $dif = $value - $mean;
 $dif2 = $dif * $dif;
 $add2 += $dif2;
 $add4 += ( $dif2 * $dif2 );
 } // foreach values
 
 $variance = $add2 / floatval( $numValues );
 return ( $add4 * $numValues ) / ( $add2 * $add2 ) - 3.0;
}