Understanding Threshold-based Auto-labeling: The Good, the Bad, and the Terra Incognita

Harit Vishwakarma, Heguang Lin, Frederic Sala, Ramya Vinayak

Keywords: Auto Labeling, Active Learning, Data Labeling, Crowd Sourcing

TL;DR: In this work we analyze threshold-based auto-labeling (TBAL) that is getting widely used in practice for data labeling. Our work provides insights on when machine-labeled data obtained through TBAL can be relied on.

Abstract: Creating large-scale high-quality labeled datasets is a major bottleneck in supervised machine learning workflows. Threshold-based auto-labeling (TBAL), where validation data obtained from humans is used to find a confidence threshold above which the data is machine-labeled, reduces reliance on manual annotation. TBAL is emerging as a widely-used solution in practice. Given the long shelf-life and diverse usage of the resulting datasets, understanding when the data obtained by such auto-labeling systems can be relied on is crucial. This is the first work to analyze TBAL systems and derive sample complexity bounds on the amount of human-labeled validation data required for guaranteeing the quality of machine-labeled data. Our results provide two crucial insights. First, reasonable chunks of unlabeled data can be automatically and accurately labeled by seemingly bad models. Second, a hidden downside of TBAL systems is potentially prohibitive validation data usage. Together, these insights describe the promise and pitfalls of using such systems. We validate our theoretical guarantees with extensive experiments on synthetic and real datasets.

Submission Number: 19