Improved Estimation of Ranks for Learning Item Recommenders with Negative Sampling (Google, CIKM 2024)
This forum post introduces a Google Research paper published at CIKM 2024: *Improved Estimation of Ranks for Learning Item Recommenders with Negative Sampling*.
- Source: Google Research publications page
- Venue: CIKM 2024
- Category: Recommender Systems
- Analyzes the bias introduced by sampled softmax / negative sampling objectives when estimating ranking quality over the full item catalog.
- Proposes corrected rank estimators that account for the sampling distribution of negatives.
- Targets large-scale item recommenders where sampling efficiency is critical for training and evaluation.
- Evaluation fidelity: better rank estimates mean offline metrics (Recall@k, MRR-style measures) better predict online performance.
- Training quality: corrected objectives can improve the learned retriever/ranker without abandoning the efficiency of negative sampling.
- Industrial relevance: two-tower retrieval and sequential recommenders at Google-scale rely heavily on sampled objectives, so estimator corrections have direct production impact.
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- Actions Speak Louder than Words: Trillion-Parameter Sequential Transducers
- Bridging Language and Items for Retrieval and Recommendation
- Original paper: *Improved Estimation of Ranks for Learning Item Recommenders with Negative Sampling*, CIKM 2024. See the Google Research page for the PDF and full author list.
Context and Motivation
Large-scale recommenders cannot score every item in a billion-item catalog during training. The standard workaround is negative sampling: for each positive interaction, only a handful of sampled negatives are used in a sampled softmax or contrastive objective. However, rankings and losses computed over the sampled subset are biased estimates of the true metrics over the full catalog, which can distort both offline evaluation and model optimization. This paper studies how to obtain improved, less biased estimates of ranks when training and evaluating recommenders with negative sampling.