Analyzing test structure by multidimensional scaling

Abstract

Multidimensional scaling was used to analyze item response data for the Test of English as a Foreign Language (TOEFL) to uncover the dimensions underlying the test. Four dimensions were identified for samples varying in native language and level of English proficiency: 3 corresponded to the test's sections and 1 was an end-of-test phenomenon. Dimensions were predominantly defined by easy items and were most important for low-scoring examinees. The dimensions' importance did not differ across language groups, except for the end-of-test dimension. Major conclusions were that (a) the TOEFL measures the intended constructs; (b) the test assesses the same constructs in each language group, but the constructs are more differentiated for low-scorers; and (c) easy and difficult items differ in what they measure. Multidimensional scaling appears to be a useful method for item-level analyses of test structure. (PsycInfo Database Record (c) 2025 APA, all rights reserved)