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From Brian Chiu <>
Subject Re: How to give bias on newer item?
Date Sat, 09 Sep 2017 00:36:34 GMT
Thanks for the detailed response!  It is very helpful.
2017年9月8日 下午11:42 於 "Pat Ferrel" <> 寫道:

> With the Universal Recommender there are a robust set of business rules
> including boosting by item properties. If you add a year+week to every
> item, then in the query you boost items from a range of weeks by differing
> amounts you can implement any “decay function you want without modifying
> code. There are many ways to set this up to get the granularity you want.
> I always strongly recommend that you get cross-validation or A/B tests
> with and without and with this type of business rule modification of
> results. The UR will automatically recommend things based on the user’s
> most recent behavior so biasing by date may not provide lift in results.
> Comparing the raw results to your bias will tell you what you want to know
> and give you a baseline to improve from. If you never test raw results you
> will never know for sure that you are improving.
> We had a client who insisted on some very complex business rules because
> they had been doing something similar in the past and we got virtually 0
> lift over no recommendations (curated recommendations). We convinced them
> to try without the rules and got a huge improvement. You may not see the
> same thing but testing will tell.
> On Sep 8, 2017, at 2:20 AM, Brian Chiu <> wrote:
> Hi all.
> In a recommender, it is quite common to give a higher priority to
> newer items.  For example, when User A has created a tweet yesterday
> and another tweet today, it is better to recommend the newer one to
> the other users (assume the 2 tweets has similar property except
> creation date)
> Specifically for Universal Recommender, can we set such a bias to new
> items?  I have read through the doc and some source code, but the best
> option I can find is to set the hard limit "dataRange".  Is it
> possible to set a smooth decay to the bias?  Or can I modify the
> source code to achieve this functionality?
> I notice that elasticsearch has an option function_score query:
> current/query-dsl-function-score-query.html
> Which seems to offer a smooth decay of bias, but I have no idea if it
> can be integrated to Universal Recommender and solve the problem.  Can
> anyone point out if it looks feasible?
> And I also notice that in some old version of PredictionIO, there was
> a parameter called freshness.
> See this commit:
> 4bebe7855767532fd4d2660548d32ab1581270d8
> And this blog on freshness:
> Is "freshness" now removed?
> Sorry for asking so many question at a time.  The community here is great.
> Thanks in advance!
> Best,
> Brain

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