Scarcely a week passes without press comment on comparative standards of attainment in public exams. This is not surprising at a time when a higher proportion of the population is taking exams than ever before, when qualifications are so important to individuals and to the country, and when data are much more freely available.

Sometimes comparisons are drawn with levels of attainment or qualifications in other countries, sometimes with standards in the past, sometimes between standards in different subjects, syllabuses, awarding bodies and universities.

So have standards risen or fallen? Are they higher or lower than in other countries? Do they differ across subjects, syllabuses and awarding bodies? Judging by comments on these matters in the press, plenty of people out there are queuing up to tell us the answers. But do we know what we mean when we ask these questions? Are they worth asking? Can we answer them? These were the issues that faced a team from the School Curriculum and Assessment Authority and the Office for Standards in Education at the beginning of its recent survey of standards at O-level GCSE and A-level from 1975 to 1995.

The investigation was prompted by an analysis of changing patterns of exam results. This showed, for example, that the proportion of 16-year-olds obtaining five or more C grades at 16 plus had risen from 22.6 per cent in 1975 to 43.5 per cent in l995, with a particularly marked increase between 1987 and 1988 - the point at which GCSE was introduced.

It also showed that the proportion of candidates awarded grade A at A-level had increased from 11.4 per cent in 1989 to l5.8 per cent in l995.

Were these genuine improvements in achievement, as we had assumed - the result of harder effort on the part of teachers and students - the result of a lowering of the demands of the examination, or perhaps a mixture of both?

SCAA and OFSTED, as the bodies responsible for standards in examinations and schools, would have been irresponsible not to have investigated the matter further. We decided, in the first instance, to examine the evidence and issues in English, mathematics and chemistry.

We asked ourselves two questions: * were syllabuses, and their assessment, in a given subject more or less demanding in 1996 than they were, say, in earlier years?

* was the level of performance required at a given grade boundary equivalent to that required in earlier years?

Both questions proved difficult to answer in the context of examinations that had changed a great deal over the intervening years. In addition, there was a lack of evidence, with very few scripts being available before 1985 at A-level or l990 at GCSE. But it was also because observers differ in what they value, and are therefore liable to respond to the same evidence in different ways.

To some observers, the inclusion of a new element in an examination might make it more demanding; to others, the same element might represent a diminution in demand.

Similarly, for some, improved performance in one element at a particular grade might be felt to offset a deterioration elsewhere, while others would disagree.

The most interesting parts of the SCAA-OFSTED report, published yesterday, tackle these questions of value in the context of the agreed aims of a particular discipline. It is on the basis of their response to these issues that SCAA and OFSTED are proposing the extensive programme of action and monitoring laid down in the report.

At the centre of the programme is a further series of surveys on standards in other subjects, including French, German, physics and history.

But what did our independent consultants find in our pilot survey of mathematics, chemistry and English?

In mathematics, the picture is unclear because of the many changes in emphasis that have taken place. One striking conclusion, however, especially at 16-plus, was that there was evidence that insufficient demand is now being placed on the most able candidates.

In chemistry, the shifts in emphasis and in styles of examining made overall judgments difficult. Some of the consultants felt, however, that there was evidence of a diminution of demand in key aspects of the subject that was not wholly offset by the addition of new elements.

In English, consultants felt that the demands on candidates had not diminished across the 20-year period. At GCSE, in their view, they had increased, and at A-level had remained comparable. They found it impossible to say anything overall about grade standards at GCSE, although at A-level the conclusion for the period 1985-95 was that these had remained the same.

On one level, the very inconclusiveness of our consultants’ findings might be seen to have vindicated those who told us that the exercise was not worth doing. But that would be to miss the point. What we wanted to gain from the exercise was an understanding of how syllabuses and exams had changed during the 20-year period and a range of expert views about the nature of these changes.

What we found was that the requirements in the three subjects had shifted in a variety of ways, in response to many different pressures and concerns, and that mapping the changes allowed us to come to a judgment about their cumulative impact.

The overall conclusion of the report is that there have been too many gains over the past 20 years to want to turn the clock back to 1975. The greater breadth of syllabuses, in particular, is something that in many cases we wish to hold on to.

Nevertheless, breadth has sometimes been added at the expense of depth, and even at times of rigour. Where this has happened there has been a noticeable downplaying of some of those elements within a subject traditionally thought of as difficult or that require accuracy, recall and the application of learnt knowledge.

In mathematics, for example, there are fewer opportunities for candidates to tackle multi-step problems unaided, or to work without given formulae or without a calculator.

In chemistry, the welcome emphasis on the application of chemical knowledge has led to an unwelcome weakening of the requirement to demonstrate this knowledge in the first place.

In English, there has been a shift away from the study of challenging pre-20th century texts - such as Milton and Donne - in favour of more recent, more “accessible” and supposedly more “relevant” works.

SCAA and OFSTED’s recommendations are designed to change this balance without losing the gains. At A-level many of the recommendations will be implemented as part of the revision of A-level subject cores already taking place, and through the subsequent approval of new syllabuses. At GCSE, some of the issues were tackled by SCAA when it approved the new syllabuses introduced earlier this year. Others are for further and, in some cases, urgent review.

The SCAA-OFSTED report will disappoint some in failing to recommend the simple return to the past that they feel would solve all our problems. But it is a declaration that we should no longer drift with a tide that in recent years has too readily emphasised accessibility at the expense of rigour. It is also a reminder that GCSE and A-level are currencies that we need to guard with vigilance if public confidence is to be maintained.

Dr Philip Evans is headmaster of Bedford School and a member of SCAA. He was a member of the steering group for the SCAA-OFSTED survey of standards over time at GCSE and A-level