Scores on a yes-no vocabulary test: correction for guessing and response style

Abstract

The use of yes-no tests seems to be a promising method for measuring the size of receptive vocabulary knowledge of learners of a foreign language. Items in a yes-no test each consist of either a word or a pseudoword. Participants are asked to indicate whether or not they know the meaning of these words. This article attempts to tackle the problem of determining a meaningful score for this type of test. Such a score should contain correction for guessing as well as for participants’ response style. Three possible methods are discussed, but none of these measures appear to apply this type of correction. Signal Detection Theory is applied and a new, more accurate index is suggested. Based on theoretical as well as empirical considerations, recommendations are made about the choice for the index to be used in a yes-no vocabulary test.