Ofsted has come out of the closet on its views of publishing contextual value added scores and their use - albeit that their views seem to be something of a curate's egg, and need just as much careful interpretation as the actual CVA figures themselves.
Contextual Added Value (CVA) is the latest measure to show how well schools are serving their clients (sorry, pupils), and takes into account prior attainment (added value) and the factors in the local environment that might affect performance but are outside the school's control such as poverty or ethnicity of the local population. This is all mulched up together (good statistical term that) to give a score normalised around 1000 and with a confidence interval - which is generally not so well published as the basic score.
Ofsted has given out guidance on interpretation, for use by schools, and has said which bits of what is published should be used and which bits are meaningless - this BBC summary is quite good on this.
My gripe is this: government would like parents and guardians to have information available on which they can base their choices for their children, and later in life, similar information available to potential students so they too can choose the best route for their future. However, with literacy and particularly numeracy levels at a low ebb in England, how are people expected to interpret CVA information? Yet it is this information that will be supplied to people to make choices on.
In my view, these figures are not fit for public use, and therefore it is questionable whether there is any value in putting them in the public domain. If an absolute score has a confidence interval of 10 which could take it above or below the national average, all people need to know about an institution is that it is average. Anything more and the number is being vested with spurious accuracy, giving people lots of opportunities to make the wrong decision, as they don't understand numbers.
There is a similar link to the publication of medical findings that are too statistically complex for 99.9% of the population to understand, so now we are faced with a measles epidemic in the UK due to people panicking.
I think the "Tiger that Isn't" should be compulsory reading for everyone in the country - but that assumes a decent level of literacy too!
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