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Methodology and Technical Notes


The Progress in International Reading Literacy Study (PIRLS) is an international comparative study of student performance in reading literacy at the fourth grade. PIRLS 2016 marks the fourth iteration of the study, which has been conducted every five years since 2001. The study was developed and implemented by the International Association for the Evaluation of Educational Achievement (IEA) and is designed to measure the reading knowledge and skills of fourth grade students over time. New to the PIRLS assessment in 2016, ePIRLS provides a computer-based extension to PIRLS, assessing students' comprehension of online information. A subset of the participating PIRLS 2016 education systems participated in ePIRLS.

The PIRLS assessment is designed to broadly align with the curricula of participating countries and therefore assess concepts that are presumably taught in most fourth-grade classrooms. In addition to the reading assessment, students provide background information. School administrators and reading teachers also provide contextual information about education, school, and classroom policies which allow for cross-national comparisons of educational context which may be related to student achievement.

PIRLS was first administered to students in 36 education systems in 2001.1 In 2016, 58 education systems2 participated in the PIRLS assessment at the fourth grade, with 16 of them also participating in ePIRLS. PIRLS (and its partner assessment ePIRLS) targets students as they have transitioned from a focus on learning to read to a focus on reading to learn. In most education systems, this point is the fourth year of formal schooling or fourth grade, with an average student age of 9.5 years. For ease of presentation, student participants are referred to as fourth-grade students in reports and findings.

Each country or education system is responsible for collecting its own data following detailed international requirements for target populations, sampling design, sampling size, exclusions, assessment administration, and defining participation rates. In the United States, PIRLS is sponsored by the National Center for Education Statistics (NCES), part of the Institute of Education Sciences (IES) in the U.S. Department of Education.
These methodology and technical notes provide an overview of the study with a focus on the U.S. implementation. The notes cover the following topics:  

More detailed information can be found in Methods and Procedures in PIRLS 2016 at

1 The term "education system" refers to IEA member countries and benchmarking participants. IEA member "countries" may be complete, independent political entities or non-national entities that represent a portion of a member country (e.g., England, Hong Kong, the Flemish community of Belgium). Non-national entities are indicated by italics in the tables and figures, with the three-letter international abbreviation for their country following their name. Non-national entities that are represented by their larger country in the main results (e.g., Abu Dhabi in the United Arab Emirates, Ontario in Canada), or whose countries are not IEA members (Buenos Aires), are designated as "benchmarking participants." Benchmarking participants are included in tables and figures in a separate section. For convenience, PIRLS reports and findings use the generic term "education systems" when summarizing results.
2 This count differs from the totals in the international results because it excludes those education systems that gave the assessments to off-grade participants (e.g., to 3rd grade students). PIRLS 2016 was administered to a total of 61 education systems.