On the Generalizability and Predictability of Recommender Systems

John P Dickerson, Sujay Khandagale, Duncan C. McElfresh, Jonathan Valverde, Colin White

Abstract: While other areas of machine learning have seen more and more automation, designing a high-performing recommender system still requires a high level of human effort. Furthermore, recent work has shown that modern recommender system algorithms do not always improve over well-tuned baselines. A natural follow-up question is, "how do we choose the right algorithm for a new dataset and performance metric?" In this work, we start by giving the first large-scale study of recommender system approaches by comparing 18 algorithms and 100 sets of hyperparameters across 85 datasets and 315 metrics. We find that the best algorithms and hyperparameters are highly dependent on the dataset and performance metric, however, there are also strong correlations between the performance of each algorithm and various meta-features of the datasets. Motivated by these findings, we create RecZilla, a meta-learning approach to recommender systems that uses a model to predict the best algorithm and hyperparameters for new, unseen datasets. By using far more meta-training data than prior work, RecZilla is able to substantially reduce the level of human involvement when faced with a new recommender system application. We not only release our code and pretrained RecZilla models, but also all of our raw experimental results, so that practitioners can train a RecZilla model for their desired performance metric: https://github.com/naszilla/reczilla.

Keywords: recommender systems, algorithm selection, meta-learning, collaborative filtering

One-sentence Summary: We conduct a large-scale study of recommender system algorithms, which motivates the design of RecZilla: an algorithm selection approach based on meta-learning.

Reproducibility Checklist: Yes

Broader Impact Statement: Yes

Paper Availability And License: Yes

Code Of Conduct: Yes

Reviewers: Colin White, [e-mail]

Code And Dataset Supplement: https://anonymous.4open.science/r/anon-reczilla-51FC/

Community Implementations: [ 3 code implementations](https://www.catalyzex.com/paper/arxiv:2206.11886/code)