# Propose new functionalities for Decidim software

## #DecidimRoadmap Designing Decidim together

### Improve the score of comments

The ranking of comments uses upvotes−downvotes.

Thanks to David Ruescas (nVotes), I found a blog post from 2009 remarking that this is a wrong strategy (http://www.evanmiller.org/how-not-to-sort-by-average-rating.html). For instance, a comment with 100 upvotes and 0 downvotes and a comment with 1000 upvotes and 900 downvotes would be equally scored. One could expect this would be solved using the average rating (upvotes/(upvotes+downvotes)), however, such strategy is also inappropriate because there will be many comments with few votes and, therefore, high uncertainty.

To solve the above problem, the blog post suggests using the lower bound of the Wilson score confidence interval. Please find the formula implemented in Ruby in the blog post, as well as this detailed explanation of why Reddit is using this method https://medium.com/hacking-and-gonzo/how-reddit-ranking-algorithms-work-ef111e33d0d9

#### List of Endorsements

### Report inappropriate content

Is this content inappropriate?

## 3 comments

## Conversation with Xabier

Thanks @elaragon , this is a very valuable input. It also seems relative easy to implement. It is important to be able to explain this to participants as well. Because very complicated mathematical formulaes are hard to understand and trust on the platform is important for its success.

I totally agree, moreover, the simpler -> the easier to understand -> the "more democratic". For that reason, as shown in https://planspace.org/2014/08/17/how-to-sort-by-average-rating/, we could use Laplace smoothing instead: (upvotes+α)/(upvotes+downvotes+β) ; (for example, α=1 and β=2)

Sounds good too!

## Add your comment

Sign in with your account or sign up to add your comment.

Loading comments ...