ANNEX A5 CHANGES IN THE ADMINISTRATION AND SCALING OF PISA 2015 AND IMPLICATIONS FOR TRENDS ANALYSES Comparing science, reading and mathematics performance across PISA cycles

The PISA 2006, 2009, 2012 and 2015 assessments use the same science performance scale, which means that score points on this scale are directly comparable over time. The same is true for the reading performance scale used since PISA 2000 and the mathematics performance scale used since PISA 2003. Comparisons of scores across time are possible because some items are common across assessments and because an equating procedure aligns performance scales that are derived from different calibrations of item parameters to each other.