Active Learning Literature Survey
Burr Settles
Computer Sciences Technical Report 1648
University of Wisconsin-Madison
This is an online publication that will be updated periodically to reflect new advances in the field of active learning. Please cite the survey in your work as suggested in Section 1. Your feedback is highly welcome to alleviate errors, and to incorporate material that is either new or has been overlooked in the current version. Please send comments to bsettles@cs.wisc.edu.
Abstract
The key idea behind active learning is that a machine learning algorithm can achieve greater accuracy with fewer labeled training instances if it is allowed to choose the data from which is learns. An active learner may ask queries in the form of unlabeled instances to be labeled by an oracle (e.g., a human annotator). Active learning is well-motivated in many modern machine learning problems, where unlabeled data may be abundant but labels are difficult, time-consuming, or expensive to obtain.
This report provides a general introduction to active learning and a survey of the literature. This includes a discussion of the scenarios in which queries can be formulated, and an overview of the query strategy frameworks proposed in the literature to date. An analysis of the empirical and theoretical evidence for active learning, a summary of several problem setting variants, and a discussion of related topics in machine learning research are also presented.