Not all credits are equal: scale length bias

Valid marking systems should produce consistent scores of student achievement. Whilst this can be more readily achieved in quantitative tasks, such as maths problems, there is difficulty in establishing consistency in grading in more qualitative tasks, such as essays. While procedures for dealing with such consistency are well established it the impact of marking scale length on this remains unclear. What an assessment is ‘marked out of’ is usually left up to the individual academic to determine. This research examines differences in marks awarded to students as a result of scale length using a large sample of essays submitted by students over multiple units and years (secondary data). Our results show that marking scale length does impact the mark students receive.