Well it is also a property of the recommender. If you throw a "normal" implementation at your data it will happily estimate, correctly, that all unknown ratings are 1. it's these other variants that do something different and meaningful.
The reverse is fine -- you can use similarity metrics that don't assume ratings on data that does have ratings. No, you're welcome to make comparisons in these tables. It's valid. On Tue, Oct 25, 2011 at 9:02 PM, lee carroll <[email protected]> wrote: > Ah you did not say boolean / non boolean recommenders, you talking > about boolean preference ratings. > > Ok I think I have it. > > I'm up to chapter 5 in the mahout in action book (so please bare with me:-) > So is it fair to say table 5.1 and 5.2 should avoid the comparissons > between the top two ? >
