Revising and validating the 2000 Word Level and University Word Level Vocabulary Tests

Few researchers have undertaken detailed investigations of the reliability and validity of tests designed to measure vocabulary size. Thus, the purpose of this study was to carefully analyse and validate the revised versions of the 2000 Word Level and the University Word Level of Nation’s Vocabulary Levels Test (Nation 1990), which can be administered for the purposes of course planning and placement in language programs. In this study, 496 Japanese high school and university students completed four forms of the 2000 Word Level Test and 464 participants completed four forms of the University Word Level Test. Two new forms of each test were created and then examined using classical and Rasch item analyses. The new forms were found to be acceptably reliable (a = .84-.95), and the Rasch analysis revealed only 3 misfitting items (k = 108). In addition, these forms had statistically significant correlations with the TOEFL, particularly for the reading and grammar subsections. A variety of evidence is then presented to support the notion that the tests are unidimensional. Finally, the authors suggest further improvements and new directions for future research.