We’ve talked a lot about PISA on this show. Today we take a fresh look at the test, digging into the specifics about how the test is created and what the results can tell policy makers and teachers.My guest today is Sam Sellar, a reader in Education Studies at Manchester Metropolitan University and a Director of the Laboratory of International Assessment Studies. He has recently co-written with Greg Thompson and David Rutkowski a short book on PISA titled, The Global Education Race: Taking the measure of PISA and international assessment.