PIRLS (Progress in International Reading Literacy Study) is the fourth assessment in the current trend series, following PIRLS 2001, 2006, and 2011. There were 61 participants in PIRLS 2016, including 50 countries and 11 benchmarking entities (e.g., regions of countries as well as additional grades or language groups from the participating…

Background: Large-scale cross-national studies designed to measure student achievement use different social, cultural, economic and other background variables to explain observed differences in that achievement. Prior to their inclusion into a prediction model, these variables are commonly scaled into latent background indices. To allow…