Editing The Netflix Prize (section)

==Background==
Netflix’s recommendation engine, '''[https://www.algorithmhalloffame.org/algorithms/cinematch/ Cinematch]''', used collaborative filtering to predict user ratings for movies based on previous ratings and patterns across similar users. By 2006, [https://www.algorithmhalloffame.org/algorithms/cinematch/ Cinematch] had been refined internally for several years, but Netflix sought a significant improvement.

To enable the competition, Netflix released an anonymized dataset on '''October 2, 2006''', which included:

*'''480,189 users'''
*'''17,770 movies'''
*'''100,480,507 ratings'''
*Ratings on a '''1.0 to 5.0 scale''', in increments of '''0.5'''
*Ratings dated between '''October 1998 and December 2005'''

Netflix stated that all personally identifiable information had been removed, replacing user names with numeric IDs.

The dataset was split into training and test sets for evaluation, and submissions were measured against a hidden test set to prevent overfitting