Vocabulary Size Test

Through the years, researchers have measured vocabulary in various ways, often the methodology behind the research has lacked purpose and validity. However, Nation’s commitment to the area of vocabulary research has not only contributed vital evidence to the understanding of vocabulary knowledge but also the development of the Vocabulary Size Test (VST) (Nation, 2006; Nation & Beglar, 2007). In this review, I examine Belgar’s (2009) study “A Rasch-based validation of the Vocabulary Size Test” and Elgort’s (2012) study “Effects of L1 definitions and cognate status of test items on the Vocabulary Size Test”. Both studies evaluate the use and validity of Nation´s VST. This review examines Belgars (2009) study on the validity of VST and Elgorts

Although various vocabulary tests exist, many of them demonstrate insufficient comprehensive measurement of individual´s vocabulary size. That being said, Belgar (2009, p. 2) discusses the importance of having a vocabulary test to assist educators in creating curriculums for native and non-native speakers of English. By determining learners´ vocabulary at any given time during a course or educational program, sheds light on the impact of the program and the learners´ progression or level of word knowledge. Likewise, Belgar emphasizes the importance of the reliability of test responses and not the tests themselves, and that “test responses are a function not only of the items, tasks, or stimulus conditions but of the persons responding and the context of measurement” (Messick, 1989, p. 14). For that reason, he decided to investigate the validity of Nation´s

First, Belgar chose Form 1 of Nation’s VST, but replaced individual words at various levels to enhance reliability, control the level of difficulty, and to have a wider range of items for learners of various backgrounds (Belgar, 2009). He also sought to demonstrate that five words per frequency level would show the same accuracy as a 10 word per frequency test by creating three types of the VST, a 140-item, 70-item and 40-item VST (Belgar, 2009, p. 3). Additionally, he categorized the 19 native speakers and 197 native speakers of Japanese into 4 groups depending on their English proficiency level and the TOEFL scores of the Japanese students. Depending on the learners´ proficiency, Belgar administered the 140-item test onto the adult native speakers and advanced non-native English speakers, while the intermediate non-native English proficiency speakers answered an 80-item test, and finally the low non-native English proficiency answered a 40-item