A review of CLIL outcomes: Calling for fuller use of effect sizes and less reliance uponp

Abstract

This article reviews empirical quantitative studies concerning the outcomes of Content and Language Integrated Learning (CLIL) from the perspective of methodological rigour. This perspective advocates for fuller use of effect sizes (ESs) and less reliance upon the statistical significance (i.e., p). Regarding making fuller use of ESs, it proposes 1) reporting ESs for both statistically significant and non-significant results, 2) specifying which ES benchmark system for interpretation, 3) utilizing a topic-specific ES benchmark system, 4) valuing ES over p, and 5) interpreting ESs adequately. Regarding relying less on p, this article underscores 1) reporting exact p values and 2) using ‘statistically’ to modify ‘(non-)significant(ly)’. This review contributes to a better understanding of the inconsistent findings concerning the outcomes of CLIL. It also provides some suggestions for EAP practitioners (e.g., emphasizing reporting and interpreting ESs in their EAP teaching).