Currently, the average rating for a show seems to be a simple average of all the ratings, so it doesn't take into account how many episodes each user has watched. A more accurate depiction would be to weigh the average based on how many of the available episodes each user has watched.

Let's take a simple example: users A and B watch the first 10-episode season of a show the year it first airs. User A rates it an 8 and user B rates it a 9. After the first season of the show, the displayed average is 85%, which is correct.

A year later, the show releases a second 10-episode season. User A is super busy watching other shows, so he delays watching season 2. In the meantime, user B watches it and finds it to be terrible, so he reduces his rating of the show to a 5. The average then corrects to 65%. However, one could argue user B has a complete overview of the show in its current state, whereas user A has only watched half, so his rating should not have as much of an impact on the average. This can be achieved by using a weighted average:

(ratingA * weightA + ratingB * weightB + ... + ratingN * weightN) / (weightA + weightB + ... + weightN)

where:

• ratingN is the rating of user N


• weightN is the number of episodes user a has watched divided by the total number of available episodes for the show or season (watchedEpisodesN / totalAvailableEpisodes)

So in our little example we have the following inputs:

• totalAvailableEpisodes = 20


• ratingA = 8


• totalEpisodesA = 10


• ratingB = 5


• totalEpisodesB = 20

Meaning:

• weightA = 10 / 20 = 0.5


• weightB = 20 / 20 = 1

Leading to the following weighted average:

(8 * 0.5 + 5 * 1) / (0.5 + 1) = 60%

If you introduce a third user that watches both seasons and also rates it a 5, the weighted average method yields an average of 56%, compared to 60% for the old method.

This solves the problem of ratings for ongoing shows and people who rate shows before they fully finished them. Some would argue people should not rate shows or seasons before they finished them, but at least for shows it makes sense to do so; you would not want to wait for a show to have ended before it can have ratings, otherwise users would not be able to decide whether to pick up an ongoing show. Depending on the details of the implementation, it could probably also alleviate the issue of people rating shows/seasons before release.

https://trakt.tv/shows/the-day-i-became-a-god
https://trakt.tv/shows/by-the-grace-of-the-gods
https://trakt.tv/shows/black-mirror
(bandersnatch is special episode 2 on tvdb, but it's a separate movie https://trakt.tv/movies/black-mirror-bandersnatch-2018 also on tvdb by the way, but they don't bother to clean up their mess in tv.. )
https://trakt.tv/shows/death-note
(again tvdb has two movies listed in specials.. https://trakt.tv/search?query=Death+Note+Relight)
https://trakt.tv/shows/with-a-dog-and-a-cat-every-day-is-fun
https://trakt.tv/shows/d4dj-first-mix
(added the episode titles from official YouTube stream added on tmdb)
https://trakt.tv/shows/kaguya-sama-love-is-war
(urgh, tvdb and their adding of episodes)
https://trakt.tv/shows/hypnosis-mic-division-rap-battle-rhyme-anima
(added episode titles from Funimation on tmdb)
https://trakt.tv/shows/adachi-and-shimamura
https://trakt.tv/shows/drag-race-holland
(added al wow presents plus info to tmdb)
https://trakt.tv/shows/burn-the-witch
(it is also a movie though on tmdb https://www.themoviedb.org/search/tv?query=burn%20the%20witch ... since we're moving to one source, maybe block one of them.. I'd say the movie version).
https://trakt.tv/shows/monster-girl-doctor
https://trakt.tv/shows/le-portrait-de-petite-cossette
https://trakt.tv/shows/de-luizenmoeder
(it actually has Dutch titles on the EN translation pages but... yeah)
https://trakt.tv/shows/aggretsuko
(I don't know why they're putting movies in the special section again... also on tmdb this time, sigh)
https://trakt.tv/shows/the-worst-witch-2017
(a mod changed the dates for episode 3 and 4 wrongly and locked them... filed a report, also added missing info for later episodes and corrected some dates).
https://trakt.tv/shows/vampire-princess-miyu
(tvdb has the 1988 series listed in the special season, while tmdb has it as it's own series - which I think isn't wrong, it was made ten years prior to the 1988 one. You don't degrade something that would originally be listed as a series, down to some special episodes
I just imported the 1988 series https://trakt.tv/shows/vampire-princess-miyu-1988 and moved my own watches over manually)
https://trakt.tv/shows/kemono-michi-rise-up
(meh, tvdb got the date wrong for the first episode, and tmdb for the episode in the middle. filed a report at tmdb. should be fixed soon, they are generally fast with these reports.)
https://trakt.tv/shows/rent-a-girlfriend
https://trakt.tv/shows/mr-love-queen-s-choice
(updated all info on tmdb)
https://trakt.tv/shows/lapis-re-lights
(there's a special episode on tvdb that wouldn't be there if it weren't for me. I filed a report to get it added to tmdb too)
https://trakt.tv/shows/drifting-dragons
(someone sabotaged the airdates to match the Netflix international broadcast on tmdb. Fixed them and asked for lock.)
https://trakt.tv/shows/the-misfit-of-demon-king-academy

and please remove this already-removed-from-tmdb movie
https://trakt.tv/movies/le-portrait-de-petit-cossette-2004
https://trakt.tv/movies/vampire-princess-miyu-1988
(it's on the list to be "merged" but that list has been going on since like 2018.... can we please remove and block it from the movie section? on tvdb it's added in the special section of the 1997 series, on tmdb it's listed as its own series)

https://trakt.tv/shows/phineas-and-ferb

I just checked Phineas & Ferb on Trakt and the episode runtimes are wrong. The vast majority of the episodes are 11 minutes and this is listed as runtime for the series.
However, a lot of episodes are listed as 22 minutes when this should be 11 minutes. This makes the total runtime of the series inaccurate.
I checked TVDB (https://www.thetvdb.com/series/phineas-and-ferb) and all episodes there have the correct runtime (I checked Disney+ to verify the episode runtimes, even though Disney+ has a different episode order.) Some episode are longer than 11 minutes but TVDB has the correct runtimes for these episodes.

Also, S04E49 (https://trakt.tv/shows/phineas-and-ferb/seasons/4/episodes/49) should be removed as the episode is a special and not part of S04. On TVDB and TMDB, this episode is not listed as part of S04.

Could this be fixed?