Simple Linear Regression

This package is used to compute simple linear regression parameters using PHP. It can be used to closely mimic the output of excel regression computation add-in. For a good how-to and intro if you are unfamiliar with this feature see Excel-easy's regression example.

Installation

Add the LinearRegression package as a dependency to your composer.json file:

{
    "require": {
        "mnshankar/linear-regression": "1.0.*"
    }
}

Using the tool

The unit tests (in the tests folder) contain a wealth of information regarding the API. Basically, you load up the X and Y columns (from arrays or a CSV) and run the compute() method to generate all the regression parameters :-)

$reg = new \mnshankar\LinearRegression\Regression();
$reg->setX($this->getXForTesting());
$reg->setY($this->getYForTesting());
$reg->compute();

Note: To account for the intercept, the first element of all X arrays is forced to be 1.

Please refer to the Excel workbook named "Regression_Verification.xlsx" in the tests folder. The worksheet named "Calculated Values" contains all parameters generated by the excel add-in using data in the worksheet named "Raw Data".

The unit tests for regression computation tests/RegressionTest.php verifies that this same data is generated by the PHP package.