Colleges have complained that a new government method for measuring "value added" penalises them if their students do too well in their A-levels. In certain cases, the system, which is being developed by the Department for Education and Skills (DfES), lowers a college's value added score as more grade As are notched up by A-level students. It also adjusts scores downwards for bigger colleges because their students on average go for more qualifications and notch up more A-level points.
Having just done my annual write-up of my department's statistical data, I was stunned to read about this. We use ALIS (A-level Information System) which gives us a residual (a number around 1) which if it's greater than 1 is a Good Thing, and if it's below 1 is a Bad Thing. There's also an S (if it's statistically significant) and a three year trend. And then we also use the sparkly new ALPS (A-level Performance System) which gives us a single number, a ranking from 1 to 9, which is colour-coded, red being 'hot' (good department! Well done!) and blue being 'cold' (Bad department! Naughty teachers!) I haven't yet come across CVA, unless it's the same as 'distance travelled' which takes the form of a pretty graph.
The basic idea of any VA system is to take a large amount of data and then compare the progress made by students between testing landmarks (SATs, GCSEs, A-levels) with the average for the country in general. This data can be used to help work out if a student is progressing, or to try and indicate if a teacher, department or school are producing grades that are lower or higher than the national average (either to help them discern how effective their teaching is, or to incentivise them, or to provide a label for the general public.) But like any statistic they have a dark side. VA is much, much better than raw results when trying to evaluate education; but because the way these statistics are created is based on specific statistical judgements, the different systems give contradictory results. If you are not careful you are 'working the numbers' just as much as you do when going for exam statistics.
I confess even I, with my reasonably high level of mathematical literacy and freakish obsession with data don't understand the true meaning of the numbers. And now here's another VA system and it conflicts with the ones we use. I see a crisis looming, not least when I have to add another set of statistics to my already bloated SAR...