Implicit feedback vs explicit ratings in recsys.

hard

Answer

$Explicit: users give a star rating.$
$Rare in practice.$
$Implicit: clicks, views, time-on-page, purchases \to 'positive' signal only, no negatives.$
$Weight positive (confidence) by frequency; treat unobserved as low-confidence negatives (Hu-Koren-Volinsky weighted ALS).$
$BPR: pairwise ranking loss on 'clicked > not-clicked'.$
$Standard in industry: Spark ALS (implicit), Amazon DSSTNE, YouTube's dual-tower.$

Check yourself — multiple choice

Same thing
Explicit: star ratings (rare); Implicit: clicks/views/purchases → positive-only signal; weight confidence via frequency + BPR pairwise loss for ranking
Random
Not real

Implicit feedback: positive-only signal; weighted ALS or BPR pairwise.

#applications

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