Simulations of news aggregator voting systems

A simple simulation of different voting systems and user behavior:

• Content submission of predefined quality between 0 and 1
• A frontpage defined by a scoring formula
• Users with different expectations and voting behavior on the content of the frontpage

The plots show the quality on the X-axis and votes on the y-axis.

Hacker News

Scoring Formula:

val gravity = 1.8
val base = upvotes + 1
val score = (if (base > 0) Math.pow(base, 0.8) else base) / Math.pow(age + 1, gravity)

Observations:

• Better quality content has the chance to reach higher scores
• There are no false positives (low quality content with high score)
• There are many false negatives (high quality content with low score)
• There are outliers with very high scores
• The variation of scores is higher on higher quality content

Hacker News Normalized by Views

Scoring Formula:

val gravity = 1.8
val base = upvotes + 1
val score = (if (base > 0) Math.pow(base, 0.8) else base) / Math.pow(age + 1, gravity) / views

Observations:

• The formula stayed the same and keeps its time-based decay characteristics
• There are no more false negatives (high quality content with low score)

Only Downvotes

Scoring Formula:

val score = -(downvotes+1) * age

Observations:

• There are no false positives (low quality content with high score)
• There are no false negatives (high quality content with low score)
• The variation of scores is higher on lower quality content

Upvotes with Views as Downvotes

Scoring Formula:

val score = (upvotes-views-1) * age

Observations:

• There are no false positives (low quality content with high score)
• There are no false negatives (high quality content with low score)
• The variation of scores is higher on lower quality content

Running the Simulation

Set the preferred ranking algorithm at the top of scoring-simulation.scala:

val scoring: Scoring = RemoveDownvote

Then run:

scala scoring-simulation.scala > data

Plot the result using:

gnuplot -e "set terminal png size 1920,1080; plot 'data' using 1:2" > data.png

Related articles

• https://felix.unote.io/hacker-news-scores (analysis of scoring inconsistencies on Hacker News) (Dead Link)

Contact

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