Reporting subscores for institutions

Recently, there has been an increasing level of interest in reporting subscores for components of larger assessments. This paper examines the issue of reporting subscores at an aggregate level, especially at the level of institutions to which the examinees belong. A new statistical approach based on classical test theory is proposed to assess when subscores at the institutional level have any added value over the total scores. The methods are applied to two operational data sets. For the data under study, the observed results provide little support in favour of reporting subscores for either examinees or institutions.