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Research: Word of Mouth and Movies
Cesar Hidalgo at the University of Notre Dame and his partners studied how movie marketing interacts with word of mouth reviews and box-office success. Their theory was that movies that were marketed heavily but weren't actually very good would show strong initial sales but would drop off quickly when word got out about a film's quality. They also asked if sales for quietly released films that were actually good would grow as word spread. They tested the theoretical model against actual box-office revenue and found that their theory held true, and that the model could be used to predict future successes.
More info:
Nature News
Cesar Hidalgo Abstract