ab

AB

This gem provides you with a way to do AB testing in a deterministic way without the need for Redis or any other service.

** NOTICE **

The gem is in very early development

Since other gems need all kinds of extra services to work, and we didn't want any extra dependencies, we created a gem that will serve your users an A/B/C or whatever version based on for example a user-id

You can then use e.g. a tool like Mixpanel to track which user saw what, and make your AB testing decisions.

The gem works in a Rails and non rails environment. It's tested on ruby 1.8.7, 1.9.3, 2.1.5, 2.2.2, jruby-1.7.8 and rubinius-2.4.0.

Examples

Simple view usage

In your view (haml):

-ab(:options=>["dude","your royal highness"], :chances=>"20/80",:name=>"greeting").for(@current_user.id) do |option|
  ="Well hello #{option}"

Defining tests in a controller

You can also create a tester, for example in your app/controllers/application_controller.rb

class ApplicationController
  before_filter :ab_tests

  def ab_tests
    @greeting_test = Ab::Tester.new(:options=>["Yo", "Hello"],  :chances=>"50/50", :name=>"greeter")
  end
end

Then in your view (haml style):

-@greeting_test.for(@current_user) do |option|
  ="#{option} Bro!"

Using a Tracker

Let's say you have a hypothetical MixPanel Tracker you want to use for AB testing. You can for example implement it like this:

class ApplicationController
  before_filter :ab_tests
  after_filter :track_ab_choices

  def ab_tests
    @greeting_test = Ab::Tester.new(:options=>["Yo", "Hello"],  :chances=>"50/50", :name=>"greeter")
  end

  def track_ab_choices
    MixpanelTracker.track(@current_user, "experiment:greeting", :version=>@greeting_test.call(@current_user.id))
  end
end

What a chance!

The chances option of the ab view helper as well as in Ab::Tester takes a string as an argument. With a format using /. It normalized the chances afterwards, so the following chances result in the exact same chance distribution:

 Ab::Tester.new(:chances=>"10/60/30")
 Ab::Tester.new(:chances=>"1/6/3")
 Ab::Tester.new(:chances=>"35/210/105")

Installation

Add this line to your application's Gemfile:

gem 'ab'

And then execute:

$ bundle

Or install it yourself as:

$ gem install ab

Usage

The main class is the Ab::Tester class which takes several options as arguments:

General Usage:

tester = Ab::Tester.new(:name=>"test_name", :options=>[true, false], :chances=>"50/50")
tester.for(user.id) # Will return true or false, depending on the user.id

Ab::Tester options:

• name: Name of the tester, used as a seed to the random number generator
• options: (required) Array of options to choose from in the test, the options can be anything
• chances: (required) String representing the chances of the options e.g. "10/20/70"
• indexer: A class that responds a class level call(opts={}) which contains the logic on how to get from a value, seed and chances to a choice. See the source code of the basic Indexer.

If you use rails

You can also use the view helper ab with the exact same options as above

option 1: using the output directy

Hello there <%=ab(:options=>["stranger", "you"], :chances=>"80/20").for(@current_user.id) %>

option 2: using a block:

<%=ab(:options=>[:stranger, :you], :chances=>"80/20").for(@current_user.id) do |option| %>
  <% if option == :stranger %>
    Hello there stranger!
  <% elsif options == :you %>
    Could you please introduce yourself?
  <% end %>  
<% end %>

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request