Examining method effect of synonym and antonym test in verbal abilities measure

Many researchers have assumed that different methods could be substituted to measure the same attributes in assessment. Various models have been developed to accommodate the amount of variance attributable to the methods but these models application in empirical research is rare. The present study applied one of those models to examine whether method effects were presents in synonym and antonym tests. Study participants were 3,469 applicants to graduate school. The instrument used was the Graduate Academic Potential Test (PAPS), which includes synonym and antonym questions to measure verbal abilities. Our analysis showed that measurement models that using correlated trait–correlated methods minus one, CT-C(M–1), that separated trait and method effect into distinct latent constructs yielded slightly better values for multiple goodness-of-fit indices than one factor model. However, either for the synonym or antonym items, the proportion of variance accounted for by the method is smaller than trait variance. The correlation between factor scores of both methods is high (r = 0.994). These findings confirm that synonym and antonym tests represent the same attribute so that both tests cannot be treated as two unique methods for measuring verbal ability.