Given a reference text about IMDB, tell me how it rates movies.

As one adjunct to data, the IMDb offers a rating scale that allows users to rate films on a scale of one to ten.

IMDb indicates that submitted ratings are filtered and weighted in various ways to produce a weighted mean that is displayed for each film, series, and so on. It states that filters are used to avoid ballot stuffing; the method is not described in detail to avoid attempts to circumvent it. In fact, it sometimes produces an extreme difference between the weighted average and the arithmetic mean.

IMDB allows users to submit their reviews and ratings.  As the most extensive internet movie database and the 54th most visited website across the planet, the scale of reviews and ratings collected for movies is massive.  IMDB uses various mathematical calculations to determine the rating of movies.  Many users decide whether to spend time and money on a film solely on ratings from IMDB.  Because of IMDB's scale and impact, it is now a subsidiary of Amazon.