Sunday, August 09, 2009

School league tables: past performance is not necessarily a guide to future performance

Many of the opponents against choice in public services rely on weak arguments. “The middle class will benefit” – yet they already win by having the resources to choose through moving into catchment areas (or buying in the private sector); ”the poor don’t want choice” – yet surveys demonstrate otherwise; “what people want is a good local school/hospital/whatever” – yet choice (with competing providers) is a means to that end.

I was therefore interested to read an article in the latest bulletin of Bristol University’s Centre of Market and Public Organisation, Research in Public Policy. The authors of Are league tables any use for choosing schools?

George Leckie and Harvey Goldstein studied the statistical significance of value added scores and concluded:

... when taking account of this uncertainty, the comparison of schools becomes so imprecise that, at best, only a handful of schools can be separated from the average school or from one another with an acceptable degree of precision. This implies that publishing league tables to inform parental choice of school is a meaningless exercise, as parents are using a tool which is not fit for that purpose.

In particular, they noted the lag of over five years between the parents looking at league tables when choosing a school and the children sit their exams. Five years a long time in the life of a school.

Does this information problem blow a hole in the argument for empowering parents and other customers of public services? I would suggest not – there are other measures of performance other than exam league tables. (There may, of course, still be value in value added league tables if failing or coasting schools raise their game through being either “named and shamed” or spurred by fear of falling school rolls.) Nevertheless the research does pose more of a challenge than the arguments usually wheeled out against choice.

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