One thing I was hoping this series would shed light on was an oddity in demographic voting patterns with the ratings system.
From my own (anecdotal) observation, there's a class of films where the 'Females 45+' rating is a big outlier in the voting, with a large proportion of '1' votes. it's as if there's a gang of a few hundred users consistently downvoting films who are classed by IMDB as being part of that demographic - I don't know if it's a default setting that some bots or trolls have used or if there really are a bunch of cinephobic old women out there just watching and hating on films, but it did spark my curiosity as to what the pattern was. It doesn't happen in every film, and it's rare that you see any other demographic sticking out like this.
The best examples are critically acclaimed films with low voter counts. More popular, or less well-received films tend to have a lot of negative noise to begin with, so the effect is less noticeable, if it's there at all.
That is exactly why I generally prefer median-like average methods versus mean-like averages in these type of crowdsourced systems. Generally speaking, average votes are distributed evenly whereas the ratings on the edges are not. The movies that you gave as examples could be due to preference of voters for particular type of movies.
I don't think it would make much odds for IMDB. Sure you'll maybe negate the overly high proportion of extreme votes, but I don't think that effect is large. I did once take the top films on IMDB and remove the extreme votes, and the effect was marginal - a few films shuffled a place or so. In exchange, if you use the median, you could have polarising films - like Twilight, having their ratings change markedly over time, as people decide to start warring over it and the numbers swamp the small number of ambivalents.
For your other point, there will be voting patterns for various demographics and certain groups of people prefer certain movies. But I think the phenomenon I'm describing is a bit too extreme to be merely a bunch of old women disproportionately taking a dislike to Ikiru and then rushing onto the internet to tell the world they hate it. It is the smallest demographic IMDB has, so it's not hurting the ratings of the films in general, it's just an oddity.
From my own (anecdotal) observation, there's a class of films where the 'Females 45+' rating is a big outlier in the voting, with a large proportion of '1' votes. it's as if there's a gang of a few hundred users consistently downvoting films who are classed by IMDB as being part of that demographic - I don't know if it's a default setting that some bots or trolls have used or if there really are a bunch of cinephobic old women out there just watching and hating on films, but it did spark my curiosity as to what the pattern was. It doesn't happen in every film, and it's rare that you see any other demographic sticking out like this.
The best examples are critically acclaimed films with low voter counts. More popular, or less well-received films tend to have a lot of negative noise to begin with, so the effect is less noticeable, if it's there at all.
Here's some examples:
Army of Shadows : http://www.imdb.com/title/tt0064040/ratings?ref_=tt_ov_rt
Spartacus : http://www.imdb.com/title/tt0054331/ratings?ref_=tt_ov_rt
Ikiru : http://www.imdb.com/title/tt0044741/ratings?ref_=tt_ov_rt
Passion of Joan of Arc : http://www.imdb.com/title/tt0019254/ratings?ref_=tt_ov_rt
Breathless : http://www.imdb.com/title/tt0053472/ratings?ref_=tt_ov_rt
Z : http://www.imdb.com/title/tt0065234/?ref_=fn_al_tt_2
Barry Lyndon : http://www.imdb.com/title/tt0072684/ratings?ref_=tt_ov_rt