Standards over time

Setting the standard – how we maintain standards over time through grade boundaries and the uniform mark scale (UMS).

Grade boundaries and UMS

By grade boundary we mean the minimum mark you need to get a certain grade: for example, you might need a mark of at least 114 out of 180 for a grade C in a certain GCSE.

Exam boards endeavour to set papers at a consistent level of difficulty year on year, but it is impossible to do this precisely. Therefore, when the papers for a subject have been marked, a group of experts meets to decide how to convert the marks to grades. The experts look at marked papers from the current and previous years, then they decide what the minimum mark for each grade should be. If this year's papers are found to be slightly harder than last year's, then this year's grade boundaries will be slightly lower than last year's. Similarly, if this year's papers are found to be slightly easier, the grade boundaries will be slightly higher.

Thus, each year's grades represent the same level of performance. The process follows national guidelines and uses statistical analysis to assist the groups of experts in making their judgements.

The object of the exercise is to be fair to all students and ensure that standards are maintained. In this way, employers and higher education institutions can be assured of the consistent quality of applicants, as indicated by their qualifications.

Some qualifications, such as A-levels and some GCSE Sciences, consist of a number of units which students can take in different sittings. The difficulty of the papers may vary slightly from one sitting to another. For example, a mark of 45 in January 2006 could represent the same level of achievement as a mark of 48 in the same module in summer 2006. Therefore these marks must be put on a common scale so that both 45 (from January) and 48 (from the summer) have the same value when contributing to an overall grade. This is done by converting the initial marks to a scale called the Uniform Mark Scale (UMS) which gives equal value to work at the same level of performance, regardless of any variation in the difficulty of the papers. The UMS is a nationally agreed scale used by all exam boards and has fixed grade boundaries. The overall grade for the qualification is obtained by adding together the UMS scores for the modules.

Further information

Watch our video to find out how students' work turns into grades.

To read more about how grade boundaries are decided, see A basic guide to standard setting.

Grade boundaries for the last 12 months are available on our website. The figures are either for the qualification as a whole, or for separate papers, modules, or units as appropriate.

For more detailed information about UMS, see Guide to the Uniform mark scale (UMS).