The Benefits of Magnitude Estimation Relevance Assessments for Information Retrieval Evaluation

Magnitude estimation is a psychophysical scaling technique for the measurement of sensation, where observers assign numbers to stimuli in response to their perceived intensity. We investigate the use of magnitude estimation for judging the relevance of documents in the context of information retrieval evaluation, carrying out a large-scale user study across 18 TREC topics and collecting more than 50,000 magnitude estimation judgments. Our analysis shows that on average magnitude estimation judgments are rank-aligned with ordinal judgments made by expert relevance assessors. An advantage of magnitude estimation is that users can chose their own scale for judgments, allowing deeper investigations of user perceptions than when categorical scales are used.