C-VLT: A reliable Chinese Vocabulary Levels Test for primary and secondary school learners.

This study developed the first Chinese Vocabulary Levels Test (C-VLT) designed for native Chinese learners in Grades 1 through 9, utilizing a developmental vocabulary list. The C-VLT comprises four subtests, each matched to different grade levels. Using probability proportional to size sampling, we selected 16 schools from four counties, with a total of 10,460 students participating in the test. Analyses combining classical test theory (CTT) and item response theory (IRT) showed that the test exhibited reasonable difficulty and discrimination, and no items showed differential item functioning effects, indicating high item quality and satisfactory test fairness. Additionally, all four subtests demonstrated high CTT reliability, and the IRT information curves and standard errors indicated good measurement precision for most students. Furthermore, evidence based on test content, internal structure, and theoretically expected relations to educational stage and word frequency supported the intended interpretation of C-VLT scores as indicators of recognition-based receptive Chinese vocabulary knowledge and stage-based vocabulary mastery. Item difficulty also generally increased as word frequency decreased and educational stage increased. Taken together, the C-VLT provides reliable and interpretable scores for assessing learners' receptive Chinese vocabulary knowledge across educational stages.