We’ll do this in three steps: first, we’ll subtract the overall mean rating (across all films and users) so that our adjusted ratings are centered at 0. Next, we’ll do the same thing for each film, to account for the mean ratings of a given film differing. Finally we’ll subtract off the mean rating for each user—this accounts for individual variations (e.g. one user giving consistently higher ratings than another).
The four ratings are None, Mild, Moderate, and High. There is also a fifth category called DIRT, explained more below. Note that the ratings all have handy color-coded graphics so you can identify the ratings with just a quick glance: green for none, yellow for mild, orange for moderate, red for high, and black for DIRT. In 1968 the Motion Picture Association of America (MPAA) established a system of movie ratings for parents to use as a guide to determine the appropriateness of a film's content for children and teenagers. The ratings system is voluntary, and there is no legal requirement that filmmakers submit their films for rating.
the KIDS FIRST! Film Festival is a showcase for new and classic children's films, TV shows and DVDs from studios, independent producers and youth producers worldwide that travels to more than 100 venues annually and has more than 10,000 screenings of individual titles throughout the year. The movie rating system used in the United States was created in 1968, as a replacement to the Hays Production Code. The Hays Production Code simply gave the Production Code Administration's approval or disapproval of a movie, without any gradation to describe the movie's content. The Hong Kong motion picture rating system (Chinese: 香港電影分級制度; Jyutping: hoeng1 gong2 din6 jing2 fan1 kap1 zai3 dou6) is a legal system of movie screening and rating. An official government agency issues ratings for any movie that will be shown in Hong Kong cinemas.