Today is “school league tables” day. Performance tables are released for schools and colleges in England, reporting a number of different measures of the exam performance of their students. While much attention this year will focus on the reporting of the new “English Baccalaureate”, we ask a more fundamental question: are school league tables in general any use to parents? One of the major aims for school league tables is to support and inform parents in choosing a school for their child: but are they fit for this purpose? The answer is “yes” – we show that using school league tables does help parents to identify the school in which their own specific child will do best in her future exams.
Parents consistently rank academic standards as being one of the most important criteria for choosing a school. The performance tables provide outcome measures that are very widely reported and easy to get hold of. The idea is that parents can scrutinise the results and weigh up the merits of the local schools, considering the academic performance, travel distance, the child’s own wishes and other factors before deciding which schools to write down on their application form.
But this idea has been subject to a number of critiques. There are three main lines of argument. First, it is argued that differences in raw exam performance largely reflect differences in school composition; they do not reflect teaching quality and so are not informative about how one particular child might do at a school. Second, schools might be differentially effective so that even measures of average teaching quality or test score gains may be misleading for students at either end of the ability distribution. Different school practices and resources might be more important for gifted students or others for low ability. Third, it is argued that the scores reported in performance tables are so variable over time that they cannot be reliably used to predict a student’s future performance. After all, today’s league tables reflect last year’s students’ exams, but a parent wants to know how her child will do in five years time.
It is an empirical question how quantitatively important these points are: are league tables helpful or not? The question on academic standards that parents want answered is: “In which feasible choice school will my child achieve the highest exam score?”. We argue that the best content for school performance tables is the statistic that best answers this question.
To answer this question, we use the long run of pupil data now available to researchers. We can follow students through their years at secondary school and see how they did in the exams at the end; that is standard. But we can also use statistical procedures (details) to estimate the counter-factuals of how that student would have done if s/he had gone to a different local school. We can then ask: if families had picked schools according to the league table information available at the time, would that have turned out to have been a good choice in terms of subsequent exam performance for that specific child? Focussing on the simplest measure of the school’s %5A*-C score, the results show that while it certainly does not produce a good choice for everyone, it produces a good choice for twice as many students than it produces a poor choice for. So on average, a family using the schools’ %5A*-C scores from the league tables to help identify a school that would be good academically for their child will do much better than the same family ignoring the league table information.
So are the league tables useful for parents? Definitely. Can they be improved? Certainly. The measures included in the performance tables should be judged according to their functionality, relevance, and comprehensibility. The test of functionality is the analysis just described. A measure is relevant if it informs parents about the performance of children very similar to their own in ability and social characteristics. It is comprehensible if it is given to them in a metric that they can meaningfully interpret. In fact, none of the current leading performance measures score very well across our three criteria. We have proposed an alternative measure that performs better on these criteria. No measure can be perfect because there are important trade-offs between relevance, functionality and comprehensibility: the more disaggregate the form in which performance tables are provided (increased relevance), the less precision they will have (decreased functionality). The more factors are taken into account in describing school performance for one specific child (increased relevance), the more complex the reported measure will be (decreased comprehensibility). Any choice on the content of league table information has to make decisions on these trade-offs.