ALL London branch
Last update: 27/05/2012
Addenda to statement 1
references to CEM information highlighted in TES article 31/3/06
Additions to Statement from CEM report
Methodologyto be inserted after "Historical context"
When comparing the grades gained by pupils in different subjects, you can either do the comparisons on the basis of
i) PANDA Relative Performance Index (RPI) - for each pupil, compare the difference between the grade (score) in the particular subject, and the average grade (score) of that pupil in all their other subjects.
ii) Durham CEM Rasch model (publ. Mar 06) - This looks at the probabilities (odds) of a pupil who gets a certain grade in one subject getting a certain grade in another. The model then calculates "difficulties" for subjects and grades that best match all the combinations of pupils, subjects and grades. "The grade difficulty depends on the relative probabilities of that grade being achieved by candidates of different ability, as determined by their performance in all their subjects and taking into account the different difficulties of all the grades they have gained." These "difficulties" can then be converted back into "grade" units for comparison and dicussion. Note that the higher the number the more "difficult" the subject, which is the opposite way round to the prior attainment analysis (where comparable pupils will be gaining lower numbers in the more "difficult" subjects).
Outcomesto be inserted in 1. GCSE after "DfES value-added"
In practice, all three methods give similar outcomes. In particular, for MFL at GCSE, the CEM Rasch model gives a very similar outcome to the other two methods. For grade C, French, Spanish and German are half a grade more "difficult" than subjects such as Science (dual), Geography, History, Maths, and a grade more "difficult" than English, PE, Drama, DT and Art.
Commentaryto be inserted before "Summary"
The research from CEM was reported on in the TES on 31 Mar 2006. Some extracts from the TES article and the CEM website follow: