Interpreting gender gap issues in standardized tests: definition and application of a theoretical tool

Gender gap in STEM disciplines is a phenomenon that has been extensively studied and described. In this paper we focus on the gender gap in mathematics and firstly we illustrate the international and national situation that emerges from the reports of large-scale assessment. The core of our work then is the definition and explanation of the gender gap index (Formula presented.), a theoretical tool which allows us to categorize the results of each item in terms of the resulting gender gap. Lastly, the index is used to analyse some items taken from INVALSI tests and it is compared and contrasted with other indexes commonly used, in order to give an example of its possible use in research in mathematics education.