mfasanya / basic-stats

Basic statistical functions for Ruby collections, such as mean, standard_deviation, z, and outlier detection

Basic::Stats

Basic statistical functions for Ruby collections, such as mean, standard_deviation, z, and outlier detection

Installation

Add this line to your application's Gemfile:

gem 'basic-stats'

And then execute:

$ bundle

Or install it yourself as:

$ gem install basic-stats

If you aren't using rails, you may have to require the basic/stats file.

require 'basic/stats'

Usage

To use basic stat's methods, include the module in your array

  array = [1,2,3,4,5,6,7,8,9,10]
  array.extend Basic::Stats
  array.mean
  array.standard_deviation
  array.critical_z
  array.z(5)

Once you've included the module, you can also use outlier detection

  array = [1,2,3,4,5,6,7,8,9,30]
  array.extend Basic::Stats
  array.select_outliers
  array.reject_outliers
  array.reject_outliers!  

Notes on outlier detection

basic-stats uses the Grubb's test for outlier detection. Specically it assumes an alpha of 5%, meaning you will mistakenly identify an outlier in 5% of your samples. More information here.

The Grubb's test does not work well for detecting multiple outliers.

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Make your changes
4. Make sure the specs run (bundle exec rake spec)
5. Commit your changes (git commit -am 'Add some feature')
6. Push to the branch (git push origin my-new-feature)
7. Create new Pull Request