The current study aims to examine whether topic familiarity can be associated with, and can also substantially contribute to, the testlet effect often found among items sharing a common passage in reading comprehension tests, particularly by using the Multidimensional Item Response Theory (MIRT) bifactor model as the main data analytic scheme. Data analyzed in this study were item scores collected from 830 Korean high school students who took a 8-passage, 32-item reading comprehension test (4 items per passage) and a 40-item self-reported topic familiarity questionnaire (5 items per passage). The results of analysis revealed that (a) the bifactor model best fit the test data; (b) the self-reported topic familiarity score was not correlated with the testlet factor scores at a statistically significant level; and (c) the overall topic familiarity score had a positive correlation with the general reading ability score, however. Implications of these major findings are discussed in terms of the usefulness of the bifactor model and the nature of testlet effects in reading tests, along with avenues for further investigation.

Laufer, Elder, Hill, and Congdon (2004) proposed the vocabulary strength framework reflecting the process of vocabulary knowledge development with a hierarchical order of four strength modalities: passive recognition, active recognition, passive recall, and active recall. Employing this framework, the present study aims to empirically examine its generalizability to EFL contexts and further explore its availability to validating the TEPS vocabulary section. Three sets of web-based tests for three proficiency groups (beginner (n=37), intermediate (n=31), and advanced (n=30)) are developed with words from three frequency bands (3000, 5000, and 7000). The test includes four sections representing four strength modes and an optional TEPS section for the two upper groups. A one-parameter Rasch model analysis reveals that item difficulties agree to the hierarchical sequence of difficulty order in the framework. Different vocabulary growth rates were found across modes and word bands. The TEPS item difficulties that are closer to recall than recognition may give a theoretical account of the measuring construct that the TEPS items tap upon.