So first of all, I apologize for posting this on this crappy-ass blog I just made. But this really wouldn’t work as a reddit comment, and this was the easiest way for me to throw something like this up.

Recently, I’d noticed that stories on reddit were behaving differently than I remembered them doing so in the past. There were less net votes for stories, and more downvotes for stories. So I went back to 3 months ago, to see if my memory was accurate, or I was just being an idiot. Here is the latest 25 number one stories on reddit.. As you can obviously see, no stories have more than 400 net votes. Compare this to 3 months ago where you can see that, in fact, no story has less than 400 net votes. If you go into a little more detail comparing the stories now versus then, it also appears that stories had less total downvotes back then, than they did now.

Now, I used to do a lot of fooling around and experimenting, to get a sense of how reddit worked. At around the time that I first noticed that stories had less total votes and such, two major changes had been made to the way reddit worked. One, the algorithm for how stories got onto the front page, and how long they stayed on the front page was changed. Two, a new protective feature was implemented to cancel out people running scripts, or acting like bots. You see, this was around the time where people were complaining incessantly about “vote-up” posts – all that fun stuff. People had started even started writing greasemonkey scripts to automatically downvote every post by certain users, or with certain words in their headlines.

Now this was obviously unfair, and counter to what reddit stood for (and in fact, potentially destructive to the nature of reddit itself). So (I’m assuming) in response to this, any account that was acting ‘suspiciously’ had it’s votes instantaneously cancelled out. If you voted a story up, a downvote would automatically appear at the same time, and vice versa. This feature is still in effect today on reddit, to the best of my knowledge.

With this in mind, I hypothesized that the reason why stories were getting less net votes, and more total downvotes, was due to a combination of these factors. But first, I had to test whether there was actually a statistically significant difference between then and now. So I did some good old fashioned t-testing.

I took the total number of upvotes, downvotes, net votes, and total votes from the 25 sequential most recent number one stories, and 25 sequential number one stories from about 2.5 months ago (almost 3 months). I then calculated the average, and standard deviations for each one of these categories. Using these values I performed either a simple T-test, or a Welch’s T-test, where appropriate, to compare the averages, and see if there was a statistically significant difference.

This is my raw data (recent data on the left, older data on the right):

The results were (with an alpha value of 5%):

Probability of 0% (p=0.00) that the observed decrease in average upvotes was due to chance. (significant, as 0 0.05)

Probability of 1.29% (p=0.0129) that the observed increase in average downvotes was due to chance. (significant)

Probability of 0% (p=0.00) that the observed decrease in average net votes was due to chance. (significant)

Probability of 9.02% (p=0.0902) that the observed decrease in average total votes was due to chance. (not significant, as 0.0902 > 0.05)

This disproves the hypothesis that the observed change was due to votes being cancelled out, as it would be predicted that there would be an increase in the number of total votes (as now, people would be getting two votes, one up, one down). The observed numbers showed that there was no statistically significant difference in the net number of votes for stories.

I’m not sure if this proves or disproves the hypothesis that the change is due to the change in the front page algorithm, as it’s impossible to predict what the results of that change would be. It’s possible that this is the reason why, but for some reason, I don’t think so. Or at least I don’t think that explains all of it.

If you look at the numbers, you’ll see that the major difference is that relative to a couple of months ago, there is a significant decrease in upvotes, and a significant increase in downvotes.

The question is still up in the air then – why did this happen, and why did it happen so suddenly?