Statistic

This small javascript library is containing statistic functions for regression analysis.

Including file

Write <script language="javascript" type="text/javascript" src="statistic.js"></script> to your head.

Use

Example:

var myArray = [l,2,3,4];

var result = statistic.arithmetic_mean(myArray);
 
// result = 2.5

Functions

valid_input(array)

Checking, if elements of input array are rational numbers.
Return value is true, if all elements are rational numbers or returning false if not.

arithmetic_mean(array)

Calculating the arithmetic mean of input array.
Return value is arithmetic mean on success and NaN on failure.

median(array)

Calculating the median of input array.
Returning median on success and NaN on failure.

standard_deviation(arr)

Calculating the standard deviation of input array.
Returning standard deviation on sucess and NaN on failure.

pearson_correlation_coefficient(arrayX, arrayY)

Calcutaing pearson correlation coefficient of input array.
Returning pearson correlation coefficient and NaN on failure.

correlation_coefficient(arrayX, arrayY)

Calcutaing correlation coefficient of input array.
Returning correlation coefficient and NaN on failure.

regression_function(arrayX, arrayY)

Calcutaing regression function of input array.
Returning array with arr[0] = k and arr[1] = d and NaN on failure. Using function Y = K*X + D .

predict_y(k,d,y)

Calcutaing x with given parameters from regression_function
Returning x and NaN on failure.

predict_x(k,d,x)

Calcutaing y with given parameters from regression_function
Returning y and NaN on failure.

Notes

Make sure that, if you are using pearson_correlation_coefficient , correlation_coefficient or regression_function, your input arrays are matching each other.

For example:

Your data

 X  #  Y
#########
1.0 # 2.0
1.3 # 2.6
1.7 # 2.4
2.1 # 2.7
2.0 # 2.8
2.5 # 3.0

Your array have to be like this:

var arr1 = [ 1.0, 1.3, 1.7, 2.1, 2.0, 2.5 ] -> All X values
var arr2 = [ 2.0, 2.6, 2.4, 2.7, 2.8, 3.0 ] -> All Y values

Matching

arr1[0] -> arr2[0]
...
arr1[i] -> arr2[i]   == X -> Y