Simple theory of IMDB bias

taw

IMDB top 250 list is dominated by old movies, which conflicts with my perception (shared by majority of people as far as I can tell) that new movies are far better than old movies (comparing either top with top or average with average).

I have a simple theory why IMDB is wrong:

For new movies, very wide population have seen it, many not fans of the genre. They vote on IMDB soon after watching.
For old movies, only narrow population of fans have seen it recently. The only people who vote on IMDB are those who've seen it recently (atypical fans), or have particularly good memories of it (atypical fans again). People who watched an old movie ages ago but don't remember much about it are very unlikely to vote on IMDB.
Therefore it's much more difficult for a new movie to get a good IMDB score than it is for an old movie.
Therefore a new movie with identical IMDB store is likely much better than an old movie with identical score.

The "correct" procedure would of course be gathering random sample of people, showing them random movies, and asking for ratings just after the movie. For practical reasons this cannot really be done, so the next best thing we can do is ignoring old movies with unreasonably high IMDB scores.

I have a simple theory why IMDB is wrong:

For new movies, very wide population have seen it, many not fans of the genre. They vote on IMDB soon after watching.
For old movies, only narrow population of fans have seen it recently. The only people who vote on IMDB are those who've seen it recently (atypical fans), or have particularly good memories of it (atypical fans again). People who watched an old movie ages ago but don't remember much about it are very unlikely to vote on IMDB.
Therefore it's much more difficult for a new movie to get a good IMDB score than it is for an old movie.
Therefore a new movie with identical IMDB store is likely much better than an old movie with identical score.

Null hypothesis from the data I've referenced in my other comments: approximately 37 movies from the '90s.

Actual data: 40 movies from the 1990s in the top 250. So signs point to movie quality being essentially constant across time (at least on the decade level of granularity. I'll take another look at specifically 1998-2003; the five years after being acquired by amazon in which presumably the site had the most traffic, but I feel like I'm privileging the hypothesis here.)

6 from 1998, 6 from 1999, 5 from 2000, basically exactly what I'd expect, nothing super high.

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Simple theory of IMDB bias

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Simple theory of IMDB bias

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