Virality trends in reddit’s default subreddits

For the past week, I’ve been mapping out virality trends on various subreddits to better understand how posts go viral on reddit. It just so happens that the time period I sampled over covered the week that the reddit admins made a huge change to the default set of subreddits. By mapping out the hotness before and after the default set was changed (05/07/2014), we can get a unique look at how the new default configuration has affected the subreddits involved.

Previous defaults

In a surprising move, the admins removed both /r/AdviceAnimals and /r/bestof from the default list. I won’t speculate as to why that happened, but these subreddit’s demotion has already had noticeable effects in the past week. /r/AdviceAnimals seems to be slowly going the way of /r/fffffffuuuuuuuuuuuu (i.e., steadily losing virality), and /r/bestof hasn’t had a viral day since the change over.



New defaults

I was lucky enough to already be tracking a handful of the new defaults before they were promoted. Most of the new default subreddits, such as /r/Art, /r/Documentaries, /r/mildlyinteresting, and /r/tifu, saw a huge spike in virality the day they were promoted.





/r/dataisbeautiful also saw a initial spike in virality, but seems to be dropping back down to previous levels. I’ve been moderating /r/dataisbeautiful and we’ve been keeping a tight reign on what gets posted there, which may explain why we haven’t seen a steady rise in virality. The nice part is that we don’t seem to have a gap in viral posts on the weekends any more!


Whereas /r/DIY, true to its name, seems to have built up most of its virality already before it became a default.


Veteran defaults

Oddly enough, some of the veteran defaults that remained defaults seem to have been affected by this new setup. Both /r/IAmA & /r/videos have dropped in virality in the past week. It looks like they were already dropping in virality for a couple weeks before the changeover, though, so perhaps their fall is already a foregone conclusion.



Meanwhile, most of the veteran defaults, such as /r/funny & /r/pics, have remained relatively unscathed.



Dr. Randy Olson is a Senior Data Scientist at the University of Pennsylvania, where he develops state-of-the-art machine learning algorithms with a focus on biomedical applications.

Posted in analysis, data visualization, reddit Tagged with: , , , , , ,
  • Zac Shaw

    Great insight!

    You could say reddit’s default subreddits are really the “front page of the internet” and all the rest are the interior pages.

  • This is really nifty! Thanks for tracking and sharing all of this. I also really liked the presentation/coloring/what you chose to highlight.

  • Dylan

    Do you know what the cause of the early spike in virality was for DIY? A certain bestof post that reached the front page?

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