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From Sean Owen <>
Subject Re: Implicit preferences
Date Sun, 10 Feb 2013 16:55:42 GMT
I think you'd have to hack the code to not exclude previously-seen items,
or at least, not of the type you wish to consider. Yes you would also have
to hack it to add rather than replace existing values. Or for test
purposes, just do the adding yourself before inputting the data.

My hunch is that it will hurt non-trivially to treat different interaction
types as different items. You probably want to predict that someone who
viewed a product over and over is likely to buy it, but this would only
weakly tend to occur if the bought-item is not the same thing as the
viewed-item. You'd learn they go together but not as strongly as ought to
be obvious from the fact that they're the same. Still, interesting thought.

There ought to be some 'signal' in this data, just a question of how much
vs noise. A purchase means much more than a page view of course; it's not
as subject to noise. Finding a means to use that info is probably going to

On Sat, Feb 9, 2013 at 7:50 PM, Pat Ferrel <> wrote:

> I'd like to experiment with using several types of implicit preference
> values with recommenders. I have purchases as an implicit pref of high
> strength. I'd like to see if add-to-cart, view-product-details,
> impressions-seen, etc. can increase offline precision in holdout tests.
> These less than obvious implicit prefs will get a much lower value than
> purchase and i'll experiment with different mixes. The problem is that some
> of these prefs will indicate that the user, for whom I'm getting recs, has
> expressed a preference.
> Using these implicit prefs seems reasonable in finding similarity of taste
> between users but presents several problems. 1) how to encode the prefs,
> each impression-seen will increase the strength of preference of a user for
> an item but the recommender framework replaces the preference value for
> items preferred more than once, doesn't it? 2) AFAIK the current
> recommender framework will return recs only for items that the user in
> question has expressed no preference for. If I use something like
> view-product-details or impressions-seen, I will be removing anything the
> user has seen from the recs, which is not what I want in this experiment.
> Has anyone tried something like this? I'm not convinced that these other
> implicit preferences will add anything to the recommender, just trying to
> find out.

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