The Leaving Cert is meant to treat all students equally, but some are treated more equally than others when it comes to marking the papers, writes Emmet Oliver, Education Correspondent

The Leaving Cert is supposed to be one of the last remaining institutions in Irish life which has not been sullied or corrupted over recent years.

The great leveller, the exam, has managed to retain huge public confidence despite the obvious stress it places on students every year and despite its obvious shortcomings as a form of assessment.

Because it has remained resistant to the twin forces of favouritism and stroke- pulling, the exam has acquired "sacred cow" status to many in the education community. For some, to question the Leaving Cert is akin to questioning the family, the Irish football team, life itself. Consequently, some of the Leaving Cert's more troubling idiosyncrasies barely merit a mention each year. One of those - the apparent inconsistency in marking - rarely gets anybody in the teaching profession or the Department of Education hot under the collar, even in June.

For them, the Leaving Cert is a bit like a car. As long as it gets you to work every morning, who really cares what is happening under the bonnet?

However, the National Council for Curriculum and Assessment (NCCA), the Points Commission and several other education bodies have raised the rather troubling issue of how different Leaving Cert subjects are marked.

The analysis produced by the NCCA and the Points Commission have concluded that some subjects are marked considerably harder than others. In other words, grades differ widely between subjects during the same year.

Students who are making their way to the English exam this morning will know this more than anyone. Many of them will have chosen particular subjects based on their own forensic investigation of how grades are allocated. But students are often castigated for this. Some education figures like to say you should select subjects because of their intrinsic merit, not their points value. But we can hardly blame students for playing the "points game" when that is the system we have created for them in the first place.

The NCCA and the Points Commission have asked the Department over the last few years to conduct an investigation into this area, but so far, at least publicly, no report has issued. So what exactly is going wrong and who is responsible? Well the Leaving Cert marking process is controlled at the top by a team of senior civil servants based in Athlone. Beneath them, a chief examiner (normally a Department of Education inspector) has responsibility for the marking of individual subjects. Below him or her is a team of "advising examiners" who sample the work of the ordinary examiners, who are virtually all practising teachers.

While the ordinary examiner has the most say in what happens to your paper, the overall system is controlled by those further up the chain of command. The chief examiner and others make sure that from year to year the grade allocations in each subject are relatively similar.

If you examine the grades awarded in most Leaving Cert subjects every year, a familiar curved pattern emerges. The line starts out low and flattened for the A and B grades, rises in the middle for C and D grades and then flattens again for fail grades. While the figures do change each year, the curved pattern rarely become radically altered. These curved distribution patterns are the key to consistency in the marking of State exams. They are the last line of defence against potential irregularities in the marking process.

Chief examiners, who are responsible for marking in each subject, get anxious when they see a sudden shift in the pattern in a particular year. Or at least they should do. This rigid system is based on the belief that the academic ability of students remains relatively constant, at least over short periods, thus ensuring there should be no sudden shifts in the grades.

So everything is tightly controlled and operates in a fair way? Er, not quite. The problem is not really about keeping standards similar within subjects year to year. It is about having equality between the subjects every year.

Take last years results as a prime example. Over 80 per cent of those doing higher-level maths got an honours grade, compared with about 66 per cent of those doing higher-level physics. The obvious severity of the marking in physics is made worse when you consider the huge number of students who do both subjects. This was not an isolated example. Take the commercial subjects: more than 76 per cent of accounting students were awarded an honours grade, but only 68 per cent of business students were given such a distinction.

The recently released report by the Taskforce on the Physical Sciences looked at these grade differences and produced even more revealing figures. For example, it found that students sitting chemistry were marked one-and-a-half times more severely than students doing most of the other subjects. The report also found that the average score (at higher level) for all subjects was a B2 or B3, but for chemistry it was about a C1. This disturbing trend goes back a good few years. The NCCA found that in 1997 you were almost five times more likely to get an A1 in higher-level accounting than Irish.

There are many more examples, but it is clear there are widespread differences in how subjects are marked. The taskforce summed it up: "A clear pattern is apparent. Students sitting the physical sciences, along with maths and French, do less well on average than students sitting other subjects." The taskforce - which did sterling work in charting a future course for science subjects - suggests the Department takes action in this area immediately and comes up with a plan "to ensure that the variation in severity of grading between Leaving Certificate subjects is minimised". Minimising would be good, but eliminating the variations entirely would be even better.

So over to you, Minister.