Structural Factor Analysis of Lexical Complexity Constructs and Measures: A Quantitative Measure-Testing Process on Specialised Academic Texts

Abstract

ABSTRACT This study evaluates 22 lexical complexity measures that represent the three constructs of density, diversity and sophistication. The selection of these measures stems from an extensive review of the SLA linguistics literature. All measures were subjected to qualitative screening for indicators/predictors of lexical proficiency/development and criterion validity based on the body of scholarship. This study’s measure-testing process begins by dividing the selected measures into two groups, similarly calculated and dissimilarly calculated, based on their quantification methods and the results of correlation tests. Using a specialized corpus of postgraduate academic texts, a Structural Factor Analysis (SFA) comprising a Confirmatory Factor Analysis (CFA) and Exploratory Factor Analysis (EFA) is then conducted. The purpose of SFA is to 1) verify and examine the lexical classifications proposed in the literature, 2) evaluate the relationship between various lexical constructs and their representative measures, 3) identify the indices that best represent each construct and 4) detect possible new structures/dimensions. Based on the analysis of the corpus, the study discusses the construct-distinctiveness of lexical complexity constructs, as well as strong indicators of each conceptual/mathematical group among the measures. Finally, a unique and smaller set of measures representative of each construct is suggested for future studies that require measure selection.