How much do students’ scores in PISA reflect general intelligence and how much do they reflect specific abilities?

International Large-Scale Assessments (LSAs) allow comparisons of education systems' effectiveness in promoting student learning in specific domains, such as reading, mathematics and science.However, it has been argued that students' scores in International LSAs mostly reflect general cognitive ability (g).This study examines the extent to which students' scores in reading, mathematics, science and in a Raven's Progressive Matrices test reflect general ability g and domain-specific abilities with data from 3472 Polish students who participated in the OECD's 2009 Programme for International Student Assessment (PISA) and who were retested with the same PISA instruments, but a different item set, in 2010.Variance in students' responses to test items is explained better by a bifactor Item Response Theory (IRT) model than by the multidimensional IRT model routinely employed to scale PISA and other LSAs.The bifactor IRT model assumes that non-g factors (reading, math, science and Raven's test) are uncorrelated with g and with each other.The bifactor model generates specific ability factors with more theoretically credible relationships with criterion variables than the standard model.Further analyses of the bifactor model indicate that the domain specific factors are not reliable enough to be interpreted meaningfully.They lie somewhere between unreliable measures of domain specific abilities and nuisance factors reflecting measurement error.The finding that PISA achievement scores reflect mostly g, which may arise because PISA aims to test broad ACHIEVEMENTS AND G-FACTOR 3 abilities in a variety of contexts or may be a general characteristic of LSAs and national achievement tests.