Re: generic latent variable recommender question

2014-01-25 Thread Tevfik Aytekin
Case 1 is fine, in case 2, I don't think that a dot product (without normalization) will yield a meaningful distance measure. Cosine distance or a Pearson correlation would be better. The situation is similar to Latent Semantic Indexing in which documents are represented by their low rank

Re: generic latent variable recommender question

2014-01-25 Thread Koobas
On Sat, Jan 25, 2014 at 3:51 PM, Tevfik Aytekin tevfik.ayte...@gmail.comwrote: Case 1 is fine, in case 2, I don't think that a dot product (without normalization) will yield a meaningful distance measure. Cosine distance or a Pearson correlation would be better. The situation is similar to

Re: generic latent variable recommender question

2014-01-25 Thread Tevfik Aytekin
Hi Ted, Could you explain what do you mean by a dithering step and an anti-flood step? By dithering I guess you mean adding some sort of noise in order not to show the same results every time. But I have no clue about the anti-flood step. Tevfik On Sat, Jan 25, 2014 at 11:05 PM, Koobas

Re: generic latent variable recommender question

2014-01-25 Thread Ted Dunning
Dithering is commonly done by re-ranking results using a noisy score. Take r to be the original rank (starting with 1). Then compute a score as s = log r + N(0,log \epsilon) and sort by this new score in ascending order. Items will be shuffled by this method in such a way that the

Re: generic latent variable recommender question

2014-01-25 Thread Pat Ferrel
For anti-flood and in the vein of “UI” you can build a recommender that recommends categories or genres then get recommendations weighted or filtered by those categories. A simple version of this is to just look at preference frequency by category for the current user. This is a lot like what

Re: generic latent variable recommender question

2014-01-25 Thread Ted Dunning
On Sat, Jan 25, 2014 at 4:33 PM, Pat Ferrel p...@occamsmachete.com wrote: BTW can you explain your notation? s = log r + N(0,log \epsilon) N?, \epsilon? r is rank N is normal distribution \epsilon is an arbitrary constant that drives the amount of mixing. Typical values are =4.

Re: generic latent variable recommender question

2014-01-25 Thread Suneel Marthi
N(0, log\epsilon) =   Normal Distribution with Mean = 0 and Variance = log(epsilon) On Saturday, January 25, 2014 7:33 PM, Pat Ferrel p...@occamsmachete.com wrote: For anti-flood and in the vein of “UI” you can build a recommender that recommends categories or genres then get