Re: Decaying score for old preferences when using the .refresh()

2013-11-24 Thread Gokhan Capan
That would be great: Specifically if that is some kind of real usage data, and the results are evaluated against a -without decay- baseline, via A/B tests measuring the increase in conversion. Best Gokhan On Wed, Nov 20, 2013 at 2:28 PM, Cassio Melo wrote: > Hi guys, thanks for sharing your

Re: Decaying score for old preferences when using the .refresh()

2013-11-20 Thread Cassio Melo
Hi guys, thanks for sharing your experiences on this subject, really appreciated. To summarize the discussion: - The decay of old preference values might loose important historical data in cases where the user has no recent activity (Gokhan) - When using decay (or truncate preferences), the precis

Re: Decaying score for old preferences when using the .refresh()

2013-11-08 Thread Pat Ferrel
> I think the intuition here is, when making an item neighborhood base > recommendation, to penalize the contribution of the items that the user has > rated a long time ago. I didn't test this in a production recommender > system, but I believe this might result in recommendation lists with better

Re: Decaying score for old preferences when using the .refresh()

2013-11-07 Thread Gokhan Capan
On Fri, Nov 8, 2013 at 6:24 AM, Ted Dunning wrote: > On Thu, Nov 7, 2013 at 12:50 AM, Gokhan Capan wrote: > > > This particular approach is discussed, and proven to increase the > accuracy > > in "Collaborative filtering with Temporal Dynamics" by Yehuda Koren. The > > decay function is paramete

Re: Decaying score for old preferences when using the .refresh()

2013-11-07 Thread Ted Dunning
On Thu, Nov 7, 2013 at 12:50 AM, Gokhan Capan wrote: > This particular approach is discussed, and proven to increase the accuracy > in "Collaborative filtering with Temporal Dynamics" by Yehuda Koren. The > decay function is parameterized per user, keeping track of how consistent > the user behav

Re: Decaying score for old preferences when using the .refresh()

2013-11-07 Thread Pat Ferrel
Not sure how you are going to decay in Mahout. Once ingested into Mahout there are no timestamps. So you’ll have to do that before ingesting. Last year we set up an ecom-department store type recommender with data from online user purchase, add-to-cart, and view. The data was actual user behavio

Re: Decaying score for old preferences when using the .refresh()

2013-11-07 Thread Gokhan Capan
Cassio, I am not sure if there are direct/indirect ways to to this with existing code. Recall that an item neighborhood based score prediction, in simplest terms, is a weighted average of the active user's ratings on other items, where the weights are item-to-item similarities. Applying a decay f

Decaying score for old preferences when using the .refresh()

2013-11-06 Thread Cassio Melo
Assuming that most recent ratings or implicit preference data is more important than the older ones, I wonder if there is a way to decrease the importance (score) of old preference entries without having to update all previous preferences. Currently I'm fetching new preferences from time to time a