This supplement contains documentation on the explicit and implicit stratification variables included in the PIRLS 2011 data files. The explicit strata are smaller sampling frames, created from the national sampling frames, from which national samples of schools were drawn. The implicit strata are nested within the explicit strata, and were used…

Progress in International Reading Literacy Study (PIRLS) provides international comparative data about students' reading achievement after four years of primary schooling, while also measuring trends over time, monitoring curricular implementation, and identifying promising instructional practices. Conducted on a regular 5-year cycle, PIRLS has…

The PIRLS 2011 international database includes data for all questionnaires administered as part of the PIRLS 2011 assessment. This supplement contains the international version of the PIRLS 2011 background questionnaires and curriculum questionnaires in the following 5 sections: (1) Student Questionnaire; (2) Home Questionnaire (Learning to Read…