A New Look into the Construct Validity of the IELTS Speaking Module

The aim of this study was to investigate the role of linguistic and intelligence factors in the Iranian IELTS candidates’ speaking performance. Linguistic factors include depth and breadth of vocabulary knowledge as well as grammar knowledge. Narrative and verbal intelligences represent the non-linguistic factors. The participants included 329 learners who took 5 validated tests and also participated in a simulated IELTS interview session. Model 1 (excluding the intelligence factors) represents the conventional view, whereas Model 2 (including all factors) is proposed for the first time in this study. The Structure Equation Modeling (SEM) was used to analyze the data. Using the SEM, both proposed models were examined to see which one fits the data more. The results of the comparisons made between the parameter estimates and fit indices of the two models demonstrate that Model 2 outfits Model 1, implying that in contrast to the conventional view, intelligence factors do play a significant and undeniable role in developing the speaking construct. Finally, the applications of the findings to promote the construct validity of IELTS are discussed.