coys25

coys25, 11 months ago

And this picture helps too: shows the decay in ranking scores for posts of different popularity (score) over time.

https://join-lemmy.org/docs/contributors/rank_algorithm.png

After a day or so, the curve flattens out. This probably explains why we keep seeing posts that are months old in “hot” - if not enough new material is being posted, after the first few pages of “hot”, posts that are 5 days old and 5 months old are essentially the same due to the exponential decay function that was chosen.

That page gives this equation:

<pre style="background-color:#ffffff;">
<span style="color:#323232;">Rank = ScaleFactor * log(Max(1, 3 + Score)) / (Time + 2)^Gravity
</span><span style="color:#323232;">
</span><span style="color:#323232;">Score = Upvotes - Downvotes
</span><span style="color:#323232;">Time = time since submission (in hours)
</span><span style="color:#323232;">Gravity = Decay gravity, 1.8 is default
</span>

My guess is that the “gravity” parameter is the issue at the moment. Something is needed to make the decay less steep, so that really old posts aren’t making it up to the top of the feed.

There might be some way of tuning the gravity parameter dynamically based on how much content is being submitted, perhaps aiming for something like “the average age of the first 200 posts should be 10 days” (I made those numbers up, but the basic idea would be that the time decay should be steeper when lots of content is submitted and less steep when content is infrequent?)

coys25, 11 months ago

After all of this, I will amend my response to say that I think that there must be something going wrong with the algorithm. Consider these two consecutive posts on my “hot” feed:

https://lemmy.world/pictrs/image/43e2ef4c-92ca-4903-9bf7-e6ffc21f1af6.jpeg

The anti-vax nonsense from two years ago was appropriately downvoted to hell. The post right underneath it is one year old and has a post score of +13. Based on the equation above, the lower post must have a higher rank than the anti-vax post, as it should have both a higher numerator and a lower denominator.

Time for a review of the source code? Or am I missing something? Do other people see this phenomenon? No older, lower-scored post should be above a newer and higher-scored post in your feed, I think.

coys25, 11 months ago

The balance is great - I almost always post and have had no problems. I think that its because the pen itself has a small profile, so while the steel adds some weight, it’s still not a very heavy or big pen overall.

coys25, 11 months ago

Another vote for Silicon Valley. Based on the list above, my guess is that this would be right up your alley!