Yes, and I'm saying that Mahout does that too, already, with AveragingPreferenceInferrer. The result will be identical to what you are suggesting. Unless I did my math wrong.
On Wed, Apr 6, 2011 at 5:51 PM, Alejandro Bellogin Kouki <[email protected]> wrote: > I agree with Sean in that the current Mahout's implementation is a Pearson > correlation, since it only considers paired items (as you said, it does not > make sense to correlate two series like that). However, the problem is that, > in recommendation, when they use this correlation as a similarity measure, > the mean of each variable (i.e., user or item) is not strictly the mean of > the observed values in the series being correlated, but it needs to consider > some extra values (those items not co-reated with the other user). > > So, perhaps this is only a notation problem, and this distance should not be > consider equivalent to that cited in the references already mentioned. >
