Inside Netflix's popular 'recommendation' algorithm
April 9th, 2012
10:04 AM ET

Inside Netflix's popular 'recommendation' algorithm

By John D. Sutter, CNN

(CNN) - Netflix recently lifted the hood on its recommendation algorithm, which helps people who use that video-streaming service to find movies and shows that they may not know about but that they would like.

The most interesting stat the company listed on its corporate blog: 75% of the videos people watch are found via some kind of recommendation that the company employs on its apps and website. That means most pieces of content people end up watching on Netflix are found with the help of a computer equation that thinks it know what you want to watch - or via Facebook, for people outside the United States (Netflix doesn't connect with Facebook in the U.S. because some say the Video Privacy Protection Act prohibits video rental records from being shared. There is some confusion over when and how that law applies.)

In any event, here's what Netflix has to say about the popularity of its digital recommendations:

We have adapted our personalization algorithms to this new scenario in such a way that now 75% of what people watch is from some sort of recommendation. We reached this point by continuously optimizing the member experience and have measured significant gains in member satisfaction whenever we improved the personalization for our members.

That's pretty remarkable. But the company admits it still has some kinks to work out.

One of them: Tailoring recommendations to individual Netflix users instead of to the entire household. Often, a family will sign up for a single Netflix account, so recommendations sometimes get muddled between what mom, dad and the kids want to watch. Netflix says in its Friday blog post that it addresses this issue by showing a "diversity" of content that would be appropriate for any member of the family.

It is important to keep in mind that Netflix’ personalization is intended to handle a household that is likely to have different people with different tastes. That is why when you see your Top 10, you are likely to discover items for dad, mom, the kids, or the whole family. Even for a single person household we want to appeal to your range of interests and moods. To achieve this, in many parts of our system we are not only optimizing for accuracy, but also for diversity.

Do you use Netflix's recommendation engine - or others like it on sites like Amazon? If so, what do you think? Where do these equations fall short and when have they gotten it right?

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Filed under: Film • Innovation • Tech
soundoff (17 Responses)
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    • Naw

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  5. MIkeSt12

    I use Netflix but do not like their "recommendation filter". Either newly acquired movies don't show up or it's full of things I would never watch. Seems like they are trying to sell us things they have been told to "push".

    April 10, 2012 at 9:32 am | Reply
  6. CNNer

    I really like the beer recommendations at ... Way better than the movie recommendations on Netflix in my opinion.

    April 10, 2012 at 9:24 am | Reply
  7. Jay

    Get off ur duffs Netflix!!!! make that distribution with HBO considering that Starz pulled over 900 movies from Netflix library in February!!! can only watch C.H.U.D. but sooo much......

    April 9, 2012 at 7:48 pm | Reply
  8. XerXeS_2012


    April 9, 2012 at 4:45 pm | Reply
  9. sara

    love their recommendations. It's one of the main reasons I use them and not amazon (even though i am a prime customer)

    April 9, 2012 at 4:40 pm | Reply
  10. Terry Clancy

    I want to be able to browse outside of what is recommended and I find Netflix's Browse, Browse by Genre, Browse by ??? and Search capabilities very lacking.

    April 9, 2012 at 12:45 pm | Reply
  11. Amanda

    I use the recommendations all the time. They're great at finding new movies and shows that you haven't heard of before.

    April 9, 2012 at 12:27 pm | Reply
    • Bhavesh

      DR, your math may work out well, but that still doesn't get at the human aspect of eojyning a film (or detesting it, for that matter). What is at issue here is Netflix's claim that they can accurately quantify the quality of a movie as it compares to customers' tastes. That's a noble and bold claim. Suffice to say I have stumbled across some really interesting plot descriptions on the Netflix recommendations, but have yet to say that it's pointed out a hidden gem to me. I can usually tell which elements of the recommended film brought it up on my profile's radar, but there's more to a good movie than a algorithmic string of similar elements. I guess I approach the recommendations with a healthy dose of Caveat Emptor. I know when I am watching a recommendation from Netflix that I may send it back without finishing it to hurry along that next movie in my queue. Kieran

      September 24, 2012 at 1:28 pm | Reply
  12. cnnlicksit

    Yeah, and Hollywood movies by and large suck eggs anyway.

    April 9, 2012 at 12:01 pm | Reply

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