Facebook and its co-founder Mark Zuckerberg, the world’s youngest self-made billionaire, are products of Harvard University, often listed as the finest university in the world. The book and movie1 about the rise of Facebook make a clear connection between the success of the company and the university where it started: both Facebook and Harvard targeted the exclusive and the elite. Facebook has recently registered its 500 millionth member.

In almost all countries students are tracked by ability into different institutions at some stage of their education. In some countries this happens relatively late – after the years of compulsory education (eg the US, the UK, and France). In other countries, this happens at the early age of 10 (eg Germany and Austria). Many European countries used to track at an early age and changed in the postwar period to tracking students when they are slightly older. This variation in practice over time and place reflects the different views on the merits of tracking. Should countries track early or late? Could they improve net educational performance by increasing the size of the ‘elite’ track? Lowering the barrier might benefit students at the margin of entry. But could this damage the education of students already comfortably past the barrier (diluting the quality of elite schools instruction) or students still left on the non-academic track (who would need to cope without their best peers)?

It is very difficult to shed light on these issues. One basic problem is that more selective areas (or countries) differ in many respects to those that are less selective. Hence a comparison of average outcomes in more or less selective education systems does not provide a credible strategy for evaluating the true effect of educational tracking. A further problem is that when educational reforms are introduced by governments they typically have a number of components. Although many European countries included de-tracking as part of their reforms in the postwar period, these reforms also had other aspects such as increasing the school leaving age. All this makes it really difficult to identify the overall effects of policies that lead to changes in ability tracking. Indeed, there is still little convincing evidence about how variation in the relative size of the elite and non-elite tracks affects average educational outcomes (see for example Manning and Pischke 2006, Figlio and Page 2002, Betts and Shkolnik 1999).

An ‘open enrolment’ reform

To address these issues, we focused our work on a unique natural experiment where the distribution of students by ability across secondary schools was modified within a given school system at a particular point in time (1989). One key feature of this experiment is that the de-tracking reform was the only change that occurred during the period of interest.

This reform, known as ‘open enrolment’, took place in Northern Ireland2 and was in the spirit of making the education system more amenable to parental choice. The secondary school system in Northern Ireland involves the distribution of students across a small set of elite schools (or grammar schools) and a much larger set of non-elite schools. Elite schools select about a third of students who obtain the best results at a national ability test taken at the end of primary school (at age 11). In 1989, they were required to accept pupils up to a new (larger) admission number determined only by “physical capacity”, where “physical capacity” was defined on a school-by-school basis by the Northern Ireland Education Department. From one cohort to the next, the number of pupils enabled to attend elite schools increased by about 15%. Most interestingly, for exactly the same cohort of pupils, we observe a strong increase in the overall number of students achieving good qualifications in the compulsory (national) examination taken at age 16 and in the number of students achieving good qualifications in the academic track at a later stage (ie A levels, at age 18), which opens the way to university education. When comparing local areas within Northern Ireland, we also find that cohorts in areas that were more affected by the reform became much more successful in national examinations than cohorts in areas that were less affected.

The main findings of the study can be illustrated using three simple figures. One can see that the jump in the number of students attending grammar schools (Figure 1) translates to a jump in the number of successful students at age 16 and 18 (Figures 2 and 3 respectively). This simple illustration of results is robust to a variety of specifications in our different empirical strategies. The analyses suggest that a 10% increase in the proportion of elite school entrants generates an increase of about 4% in the number of students achieving good grades in the compulsory public examination (ie five more A*-C grades at GCSE level) and an increase of about 7% in the number of students getting good grades in further education (ie three A levels). The data also suggest a positive effect of the reform on university attendance.

No dilution of elite education

Thus, in this case, an expansion of the elite track had a positive net impact on examination outcomes (even though the expansion took place relatively far down the distribution). This can be interpreted as the combination of three basic effects:

  • The effect of attending grammar school on pupils who would otherwise have attended another secondary school;
  • The effect of losing more able peers on students still attending non-grammar schools after the reform; and
  • The effect of having less able peers on students who would have entered a grammar school even in the absence of the reform.

Although it is not possible to identify the specific contribution of each of these effects, it is possible to provide plausible lower bounds by examining the impact of the reform separately for grammar and non-grammar schools. When we do this, we are unable to prove positive effects for those who would have always gone to non-grammar schools. However, we are able to rule out negative effects for students who would have gone to grammar school in the absence of the reform. Thus, contrary to fears expressed at the time of this reform, expanding the elite track did not dilute the quality of education in the elite institutions for high ability students.

As with all such reforms, findings cannot be assumed to hold outside the study context. Nonetheless this example provides clear evidence that at least in some contexts widening access to the more academic track can generate effects which are strong and positive and does not systematically dilute the quality of education.


Galindo-Rueda, F, and A Vignoles (2004), “The Heterogeneous Effect of Selection in Secondary Schools: Understanding the Changing Role of Ability”, Institute for the Study of Labour (IZA) Discussion Paper 1245. Bonn, Germany.

Guyon, N, E Maurin, and S McNally (2010), “The Effect of Tracking Students by Ability into Different Schools: a Natural Experiment”, CEPR Discussion Paper No. DP7977

Hanushek, EA and L Wößmann (2006), “Does Educational Tracking Affect Performance and Inequality? Differences-in-Differences Evidence Across Countries”, Economic Journal, 116:C363-C76.

Kerckhoff, AC, K Fogelman, D Crook, and D Reeder (1996), Going Comprehensive in England and Wales, The Woburn Press.

Manning A and S Pischke (2006), “Comprehensive versus Selective Schooling in England and Wales: What Do We Know?”, IZA DP No.2072.

Waldinger, Fabian (2006), “Does Tracking Affect the Importance of Family Background on Students’ Test Score”, Unpublished Manuscript, London School of Economics.


Figure 1. Variation across cohorts in the (log) number of students attending elite schools in Northern Ireland.

Note: Using the area-level data, the graph shows the change across cohorts in the (log) number of students attending grammar schools (cohort 1974 taken as a reference). The average number of students attending elite schools is 15% higher in cohort 1979 than in cohort 1978. Dotted lines show confidence intervals.

Figure 2. Variation across cohorts in the (log) number of successful students at age 16

Note: Using area-level data, the graph shows the change across cohorts in the average of the (log) number of students obtaining 5 or more GCSEs at grades A*-C (cohort 1974 taken as a reference). Dotted lines show confidence intervals.

Figure 3. Variation across cohorts in the (log) number of successful students at age 18

Note: Using the area-level data, the graph shows the change across cohorts in the average of the (log) number of students obtaining 3 or more A levels (cohort 1974 taken as a reference). Dotted lines show confidence intervals.

1 The Accidental Billionaires (2009) by Ben Mezrich and The Social Network (2010), directed by David Fincher.

2 In many respect, the education system in Northern Ireland is similar to that in England and Wales. All schools are expected to apply the same National Curriculum. There are the same national examinations. However, Northern Ireland is different because it retained early tracking and education is largely segregated by religion (Catholic and Protestant).

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