Stewart questioned vocabulary size estimation methods proposed by Beglar and Nation for the Vocabulary Size Test, further arguing Rasch mean square (MSQ) fit statistics cannot determine the proportion of random guesses contained in the average learner's raw score, because the average value will be near 1 by design. He illustrated this by…

With multiple options to choose from, there is always a chance of lucky guessing by examinees on multiple-choice (MC) items, thereby potentially introducing bias in item difficulty estimates. Correct responses by random guessing thus pose threats to the validity of claims made from test performance on an MC test. Under the Rasch framework, the…

The purpose of this research is to develop a vocabulary assessment, Evaluation of Academic Vocabulary or "EAV," that gauges students' depth of knowledge of academic words and is sensitive to vocabulary growth in the context of literacy interventions. We report results from two studies with native English-speaking middle school students…

Stewart questioned Beglar's use of Rasch analysis of the Vocabulary Size Test (VST) and advocated the use of 3-parameter logistic item response theory (3PLIRT) on the basis that it models a non-zero lower asymptote for items, often called a "guessing" parameter. In support of this theory, Stewart presented fit statistics derived from…

Validated under a Rasch framework (Beglar, 2010), the Vocabulary Size Test (VST) (Nation & Beglar, 2007) is an increasingly popular measure of decontextualized written receptive vocabulary size in the field of second language acquisition. However, although the validation indicates that the test has high internal reliability, still unaddressed…