Senior interview questionAsked at Airbnb · interview write-up
There is no text query, only structured intent such as location, dates and guests. Design the ranker for home search results, including bias from past rankings, cold start and online evaluation.
Model answer
Intent is structured: location, dates, guests, filters, plus user history. Rank by predicted booking probability from listing, user and context features.
Logged data reflects past rankings, since people click what was shown first, so correct for position bias: train with position as a feature and fix it to a constant at serving, or weight examples by inverse propensity estimated from randomised slots. New listings get content-based priors and a little exploration traffic. Evaluate offline with NDCG on bookings, then A/B test bookings and cancellations, watching new-host exposure.
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