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apple / turicreate

Turi Create simplifies the development of custom machine learning models.
BSD 3-Clause "New" or "Revised" License
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Unclear parameter in recommender.create #602

Open TobyRoseman opened 6 years ago

TobyRoseman commented 6 years ago

The API doc string for recommender.create describes the ranking parameter as Determine whether or not the goal is to rank items for each user. More detail should be provided here.

afranklin commented 6 years ago

@hoytak can you tell us more about this parameter?

hoytak commented 6 years ago

Sure. It's covered at a high level in the user guide. Basically there are two goals with a recommender system -- the first is to provide an accurate prediction of the score (i.e. the error is RMSE), and the other is to recommend items that, with high confidence, have a high score but with which you don't really care about the actual predicted score. There are a number of cases where using just a prediction of the score is bad -- e.g. an item has a single perfect rating, and the solution is to use a different objective that focuses on predicting only items that have a high score. These tend to perform much worse on RMSE errors but much better on Precision-Recall tasks.