PHPBuilder - Skewness, Kurtosis and average statistical function

# Skewness, Kurtosis and average statistical function

by: dhk
|
April 19, 2001

Version: 1.0

Type: Function

Category: Math Functions

Description: Skewness, Kurtosis, and also average function by using array methodology

```<?php
/*
In this code fraction, there r 3 function that run on mean or average and skewness and kurtosis.
Program by : dhiranuntk@hotmail.com
Date : Feb.18,2001
*/

function mean(&\$array) {
\$average = 0;
while (list(\$key, \$val)=each(\$array)) \$average += \$val;
reset(\$array);
\$average /= count(\$array);
return \$average;
}
function skewnessandkurtosis(\$array, &\$skew, &\$kurt) {
\$skew = "N/A";
\$kurt = "N/A";
\$amount = count(\$array);
if (\$amount > 2) {
for (\$i = 0, \$m2 =0,\$m3=0,\$m4=0; \$i < \$amount; \$i++) {
\$array [\$i] -= mean(\$array);
\$m2 += pow(\$array[\$i], 2);
\$m3 += pow(\$array[\$i], 3);
\$m4 += pow(\$array[\$i], 4);
}
\$m2 /= \$amount;
\$m3 /= \$amount;
\$m4 /= \$amount;
\$skew = \$m3 / pow(\$m2, 1.5);
\$skew *= sqrt(\$amount*(\$amount-1))/ (\$amount-2);
if (\$amount > 3) {
\$kurt = (\$m4/ pow(\$m2, 2))-3;
\$kurt = ((\$amount+1)*\$kurt)+6;
\$kurt *= (\$amount-1)/((\$amount-2)*(\$amount-3));
}
}
}
?>

<?
// and also example on how 2 use is here

\$samplearray = array(1.8,1.9,1.2,1.5,1.7);
skewnessandkurtosis(\$samplearray, \$skew, \$kurt);
echo "<p>Data average = ". mean(\$samplearray)."</p>";
echo "<p>skewness = \$skew </p>";
echo "<p>kurtosis=\$kurt</p>";
?>   ```

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