This indicator reflects student achievement levels across major international testing programs, standardized for comparability. Harmonized test scores are measured in TIMSS-equivalent units, where a score of 300 represents minimal attainment, and 625 indicates advanced attainment. Test scores are included from the following programs: TIMSS/PIRLS, PISA, PISA+TIMSS/PIRLS, SACMEQ, PASEC, LLECE, PILNA, EGRA, and EGRANR. The methodology is detailed in Patrinos and Angrist (2018), Global Dataset on Education Quality: A Review and Update (2000-2017). Name in source: Harmonized Test Scores.