lwc/kumite

A simple library for multivariate testing in web applications

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Language: PHP

3.0.1 2014-10-01 02:37 UTC

README

Table of contents

What is kumite?

Kumite is a framework for managing split testing.

It's purpose is to manage and track participants in split tests, as well as track events/outcomes. It makes no assumptions about how participants are allocated into variants.

Tests may be defined with a number of variants and an allocation strategy that can assign a variant to a request. Events may be tracked against variants, with optional metadata if desired. It makes no assumptions about how your application interacts with cookies or how you would like to store test data. It is named for the fictional fighting tournament, portrayed in the 1988 Jean-Claude Van Damme movie Bloodsport.

Installing

The easiest way to install is via composer: composer require lwc/kumite

Running tests

Starting tests

In order to run a test, you must first select a starting point for your test. Typically this will happen inside a controller action in your application. When starting a test, you must provide the test key of the defined test and optionally an array of metadata to attach to the test participant and allocation method that will override the method declared in the test definition. Allocators must be an instance that implements Allocator, something callable in php terms, or a constant value representing a variant.

Using a constant value:

<?php

// some controller action
function productPage()
{
  // place users into variants based on a query string value. Useful for integrating with external tools.
  Kumite::start('pricing-test', null, $_GET['v']);
}

Using the Allocator interface:

<?php

// defined elsewhere
class MyRandomAllocator implements Kumite\Allocator
{
  // selects a variant at random. Everyone gets tagged with a variant.
  public funciton allocate($variantKeys)
  {
    return array_rand($variantKeys);
  }
}

// some controller action
function productPage()
{
  Kumite::start('pricing-test', null, new MyRandomAllocator());
}

Using a callback:

<?php

// some controller action
function productPage()
{
  $user = getActiveUser();
  $metadata = array(
    'userId' => isset($user) ? $user->id : null
  );
  // place users into variants based on user id (why, who knows?!). Logged out users are disqualified from participating
  Kumite::start('pricing-test', $metadata, function($variantKeys) use($user) {
    if ($user) {
      return $variantKeys[$user->id() % count($variantKeys)]; 
    }
    return null; // user is logged out
  });
}
Varying content

There are two main ways to vary content to participants in a test, via the variant key and via variant properties:

<?php if (Kumite::variant('pricing-test') == 'lowerprice'): ?>
  <div>
    <p>Look at our new low price of <?php echo Kumite::variant('pricing-test')->property('price') ?></p>
  </div>
<?php endif; ?>

Requests that are not participating in the test will be allocated to the defined default variant for purposes of varying content, but no events will be tracked against them.

Tracking events

Tracking events in kumite is achieved by calling Kumite::event($testKey, $eventKey, $metadata=array()):

function invoicePage()
{
  // ...
  $sale->save();
  // user made a purchase, track the event in kumite
  Kumite::event('pricing-test', 'sale', array('amount' => $sale->amount()));
}

Defining tests

Tests are defined in the following format:

<?php

$config = array(
  'pricing-test' => array(
  'allocator' => new Allocators\UCB1Allocator('purchase') // there are several included allocators, or define your own
  'active' => true, // controls allocation to tests, events will still be tracked for participants 
    'default' => 'control', // defines the default variant, served to request not participating in the test. Typically the control.
    'variants' => array(
      'control', // this variant defines no properties
      'lowerprice' => array('price' => '$300') // this variant defines properties
    ),
    'events' => array('purchase', 'refund')
  )
);

Integrating with your application

Configuring

During the initialisation of your application, you need to configure kumite.

<?php

Kumite::setup(array(
  'storageAdapter' => new MyStorageAdapter(),
  'cookieAdapter' => new MyCookieAdapter(), // Optional, defaults to using PHP's $_COOKIE if not provided
  'tests' => function() {
    require_once('path/to/configuration/file.php');
    return $config;
  }
));
StorageAdapter

So that kumite can save participant and event data, you need to define a StorageAdapter.

Luckily, this is rather trivial, eg:

<?php
class MyStorageAdapter implements Kumite\Adapters\StorageAdapter
{
  /**
     * @return participantId
     */
    public function createParticipant($testKey, $variantKey)
    {
        $participant = new KumiteParticipant(array(
            'test' => $testKey,
            'variant' => $variantKey
        ));
        $participant->save();
        return $participant->id(); // Now we have a participant id, courtesy of the database 
    }

    public function createEvent($testKey, $variantKey, $eventKey, $participantId, $metadata=null)
    {
        $event = new KumiteEvent(array(
            'test' => $testKey,
            'variant' => $variantKey,
            'event' => $eventKey,
            'participantId' => $participantId,
            'metadata' => $metadata         
        ));
        $event->save();
    }

    // used for results and for intelligent allocators, such as UCB1
    public function countParticipants($testKey, $variantKey)
    {
        return Participant::getTotalForVariant($testKey, $variantKey);
    }

    public function countEvents($testKey, $variantKey, $eventKey)
    {
        return Event::getTotalForEvent($testKey, $variantKey, $eventKey);
    }
}
CookieAdapter

If your application has a specific mechanism for interacting with cookies, you will need to define a CookieAdapter so that kumite may tag requests with variant tokens.

For example, here is the source of the included default PhpCookieAdapter:

<?php

class PhpCookieAdapter implements Kumite\Adapters\CookieAdapter
{
  public function getCookies()
    {
        return $_COOKIE;
    }

    public function getCookie($name)
    {
        return isset($_COOKIE[$name]) ? $_COOKIE[$name] : null;
    }

    public function setCookie($name, $data)
    {
        setcookie($name, $data);
    }
}

Contributing

If you've found a bug or would like to contribute, please create an issue here on GitHub, or better yet fork the project and submit a pull request!