What does a scale score of 500 represent?
The scale score of 500 represents the average score for the 15 year olds who sat PISA . The ISA has directly linked its tests to PISA at Grades 7 and 9/10 by using some of the same items in the ISA as were used in PISA . The ISA tests for all the grade levels are also linked through the use of some common items, allowing us to put all the ISA items on the same scale as PISA . We have created our own ISA/PISA scale. Therefore, lower grades have lower average scale scores on the PISA/ISA scale. It does not matter which ISA test a student takes, their scale score will show their performance relative to the 500 mean for PISA 15 year olds. Any student who has a scale score of 500 is performing at the same level as the average PISA 15 year old. If a grade 7 student and a grade 10 student both have a scale score of 500, regardless of the fact that they sat different tests, they have the same level of ability in relation to the skills that ISA measures. Scale scores can be directly compared ac
