Database Reference
In-Depth Information
[8] L. von Ahn, “Games with a purpose,”
IEEE Computer Magazine
, pp. 96-98, June 2006.
1
To be exact, the algorithm had to have a root-mean-square error (RMSE) that was 10% less than the RMSE of the
Netflix algorithm on a test set taken from actual ratings of Netflix users. To develop an algorithm, contestants were
given a training set of data, also taken from actual Netflix data.
2
The rating is not a very reliable feature, but it will serve as an example.
3
Note that the fact all user-vector components will be small fractions does not affect the recommendation, since the co-
sine calculation involves dividing by the length of each vector. That is, user vectors will tend to be much shorter than
movie vectors, but only the direction of vectors matters.
