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https://github.com/instacart/wilson_score
Simple, dependency-free Wilson score
https://github.com/instacart/wilson_score
Last synced: about 2 months ago
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Simple, dependency-free Wilson score
- Host: GitHub
- URL: https://github.com/instacart/wilson_score
- Owner: instacart
- License: mit
- Created: 2013-09-28T22:42:04.000Z (almost 11 years ago)
- Default Branch: master
- Last Pushed: 2021-02-22T11:23:50.000Z (over 3 years ago)
- Last Synced: 2024-07-22T10:40:43.304Z (2 months ago)
- Language: Ruby
- Homepage:
- Size: 9.77 KB
- Stars: 156
- Watchers: 8
- Forks: 12
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE.txt
Awesome Lists containing this project
README
# Wilson Score
Simple, dependency-free [Wilson score](http://en.wikipedia.org/wiki/Binomial_proportion_confidence_interval#Wilson_score_interval)
Inspired by [How Not To Sort By Average Rating](http://www.evanmiller.org/how-not-to-sort-by-average-rating.html) by Evan Miller
## How to Use
3 positive ratings out of 5 with 95% confidence
```ruby
WilsonScore.lower_bound(3, 5)
```
[Continuity correction](http://en.wikipedia.org/wiki/Binomial_proportion_confidence_interval#Wilson_score_interval_with_continuity_correction) can improve the score, especially for a small number of samples (n < 30). As of version 0.1.0, it is enabled by default. To disable continuity correction, use:
```ruby
WilsonScore.lower_bound(3, 5, correction: false)
```
The default confidence level is 95%. To change this, use:
```ruby
WilsonScore.lower_bound(3, 5, confidence: 0.99)
```
To get the full interval, use:
```ruby
WilsonScore.interval(3, 5)
```
## Star Ratings
You have a rating system where users can rate products from 1 to 5 stars.
A product has two ratings - one 4 star and one 5 star.
```ruby
average_rating = 4.5
total_ratings = 2
rating_range = 1..5 # 1 to 5 stars
WilsonScore.rating_lower_bound(average_rating, total_ratings, rating_range)
```
## Installation
Add this line to your application's Gemfile:
```ruby
gem 'wilson_score'
```
And then execute:
```sh
bundle
```
## Additional Resources
- http://www.vassarstats.net/prop1.html
- http://www.goproblems.com/test/wilson/wilson.php
## Contributing
Everyone is encouraged to help improve this project. Here are a few ways you can help:
- [Report bugs](https://github.com/instacart/wilson_score/issues)
- Fix bugs and [submit pull requests](https://github.com/instacart/wilson_score/pulls)
- Write, clarify, or fix documentation
- Suggest or add new features