Other approach for non binary ratings is to use the true Bayesian estimate, which uses all the platform ratings as the prior probability. This is what IMBD uses in its Top 250:
"The following formula is used to calculate the Top Rated 250 titles. This formula provides a true 'Bayesian estimate', which takes into account the number of votes each title has received, minimum votes required to be on the list, and the mean vote for all titles:
weighted rating (WR) = (v ÷ (v+m)) × R + (m ÷ (v+m)) × C
Where:
R = average for the movie (mean) = (Rating)
v = number of votes for the movie = (votes)
m = minimum votes required to be listed in the Top 250
C = the mean vote across the whole report"
> To expand its user base, Power asked users to provide their Facebook credentials and then—with their permission—sent Power.com invitations to their Facebook friends. Facebook, naturally, didn't appreciate this marketing tactic. They sent Power a cease-and-desist letter and also blocked the IP addresses Power was using to communicate with Facebook's servers.
> Facebook sued, claiming that its cease-and-desist letter made Power's access unauthorized under the terms of the CFAA. Power disagreed and argued that having permission from Facebook users was good enough—it didn't need separate approval from Facebook itself.
How can be illegal if users are giving their permission? What happens if I give my permission to an external service to extract my own data?