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A New, Open Source English Vocabulary Test
Emil O. W. Kirkegaard, Meng Hu and Jurij Fedorov
Published: 2024/12/01
Abstract
Vocabulary is one of the best measures of general intelligence (g). However, readily available English vocabulary tests are often based on outdated words or are proprietary. To remedy this problem and to provide a large item pool for computerized adaptive testing (CAT), we sought to construct a new English vocabulary test. We constructed a total of 224 items using different formats (choose 1 of 5, choose 2 of 5, and choose 3 of 5). After initial experimentation, we validated and normed the test using an online US sample from Prolific (N = 441). The resulting full test had near-perfect overall reliability, 0.97. The reliability was high for a wide range of ability, above 0.90 for z scores from -3.89 to 2.32. Differential item functioning testing found negligible bias for sex. The total test score showed a small advantage in favour of women (d = 0.16) in the White sample but virtually no sex difference in the entire sample (d = 0.07). Abbreviated versions of the test were constructed based on multiple algorithms. Keywords: Vocabulary, IRT, DIF, Predictive validity, Reliability, Test optimization, Prolific, Online testing
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