The International Association for the Evaluation of Educational Achievement (IEA) is an international cooperative of national research institutions, government research agencies, scholars and analysts working to evaluate, understand and improve education worldwide. IEA is a nonprofit and independent organization. More than 60 countries are actively involved in the IEA network, and over 100 education systems participate in our studies.
IEA’s TIMSS & PIRLS International Study Center conducts regular international comparative assessments of student achievement in mathematics and science (TIMSS) and in reading (PIRLS) in more than 60 countries. TIMSS (the Trends in International Mathematics and Science Study) and PIRLS (the Progress in International Reading Literacy Study) together comprise the core cycle of studies for IEA. Headquartered in Amsterdam and with a major data processing and research center in Hamburg, IEA has been conducting international comparative studies of student achievement since 1959.
TIMSS and PIRLS enable participating countries to make evidence-based decisions for improving educational policy.
The TIMSS 2015 mathematics achievement results are reported as average scores and distributions on the fourth and eighth grade TIMSS 2015 mathematics achievement scales.
Each scale summarizes students’ performance on a large number of test items (169 at fourth grade, 212 at eighth grade) designed to measure the breadth of mathematics content, as well as a range of cognitive processes within the knowing, applying, and reasoning domains.
The TIMSS Assessment Frameworks and items are developed and reviewed through a consensus process involving all participating countries.
The TIMSS mathematics achievement scales were established in TIMSS 1995 based on the achievement across all participating countries, treating each country equally.
At each grade, the scale has a range of 0–1,000 (although student performance typically ranges between 300 and 700).
A centerpoint of 500 was set to correspond to the mean of overall achievement in 1995, with 100 points set to correspond to the standard deviation.
Achievement data from subsequent TIMSS assessments have been reported on these scales so that increases or decreases in average achievement may be monitored across assessments.
TIMSS uses the scale centerpoint as a point of reference that remains constant from assessment to assessment.