Update 16:45, 7 January 2019: The table and charts in this post were updated to strictly include figures for regulated IGCSEs, with wording also amended in one place to make this clear. The analysis, and conclusions reached, are unchanged.

In the news lull between Christmas and New Year, both the Times and the Observer reported on claims made by the Labour Party that GCSE reforms had favoured pupils in independent schools.

This seemed to be based on the assertion that IGCSEs, which are disproportionately used by independent schools, were easier than reformed GCSEs. State schools can enter pupils in some IGCSEs[1] but the qualifications don’t count in school performance tables (league tables, as they are commonly known).

In the days when IGCSEs counted in school performance tables, there did not appear to be any particular performance advantage to entering IGCSE rather than GCSE in English language.

But is the assertion true now that GCSEs have been reformed?

Now that my Quality Street-induced torpor is fading, let’s look at some data.

Are IGCSEs graded less severely than GCSEs?

To start I’m going to make some assumptions.

Firstly, that “easier” means “graded less severely”. This is a topic we’ve covered before.

Secondly, that GCSEs and IGCSEs measure the same underlying subject domains.

I’m going to look at data from summer 2017, the first year of reformed GCSEs, graded 9-1, in English and maths, looking at all pupils who reached the end of Key Stage 4 that year, including those in independent schools.

On the surface, attainment in IGCSEs was far higher than in reformed GCSEs. Two-thirds of pupils achieved grade A*-A in IGCSEs in maths and English language, whereas the fraction achieving the equivalent (grades 9-7) in reformed GCSEs was more like one-in-five, as the table below shows.

We would expect that to be the case given that the overwhelming majority of entries were in independent schools, where attainment tends to be higher.

The question is, would there still be such a disparity in attainment if those who took regulated IGCSEs had taken reformed GCSEs instead?

As a rough and ready way of answering this, I’m going to look at pupils’ results in English and maths alongside their results in old style A*-G GCSEs also taken in summer 2017. These cover all other subjects apart from English and maths. Modern foreign language subjects are left aside, as we know that they are graded too severely, as are minority subjects (those with fewer than 5,000 entries nationally).

Results in English and maths are then compared to results in these other subjects. Most pupils have several GCSEs in other subjects. In these cases, I randomly pick one. This forms the basis of the comparator bars in the charts below.

An answer of sorts

As the chart below shows, more A*-A grades were awarded in IGCSEs in English language and maths than we might expect given the comparator based on other subjects. The equivalent grades in reformed GCSEs were broadly in line with expectations.

Looking at A*-C grades, slightly more were awarded in both IGCSE and reformed GCSE English language and maths than we might expect given the comparator, as the chart below shows.

So on the basis of this quick bit of analysis, at the top end of the distribution, perhaps IGCSEs are indeed not graded quite as severely as reformed GCSEs. I’d probably want to do a bit more to ensure the comparators used are equivalent in terms of grading severity but there looks to be something in it.

9 January 2019: In response to this post, Cambridge Assessment have published a blogpost on the comparability of GCSEs and their IGCSEs. 

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1. Those regulated by Ofqual.