How do L2 writing subskills interact hierarchically? Insights from diagnostic classification models

This study examined the hierarchical structure among second/foreign language (L2) writing subskills using a Hierarchical Diagnostic Classification Model (HDCM). A pool of 500 essays composed by English as a Foreign Language (EFL) students was assessed by four experienced EFL teachers using the Empirically-derived Descriptor-based Diagnostic (EDD) checklist. Based on a literature review and the expertise of three content experts, several models were developed to reflect various hierarchical inter