TRANSPARENCY AND DISCRIMINATORY POWER OF THE LEAVING CERTIFICATE EXAMINATION

Two major issues arise when the final marks for an examination are simply the aggregate of the marks awarded for individual subjects, which happens in the Leaving Certificate Examination (LCE). The first relates to transparency, that is, the assumption that all subjects contribute equally to the aggregate mark. The second relates to the discriminatory power of the examination, that is, its capacity to distinguish between different levels of achievement. Two sets of data were analysed to address these issues: the grades awarded to all candidates in the 2001 LCE in the examinations they took, and the frequency with which the different grades were awarded in LC examinations in the surrounding decade (1998 to 2007). Results indicate that (i) in the 2001 LCE, the weights achieved by subjects deviated considerably, and to different degrees, from expected weights and (ii) for the period 1998 to 2007, there were large and consistent differences between subjects in their discriminatory power, which declined over time. Of the two, the latter is more fundamental insofar as it concerns the validity of the examination, and the unfairness that arises when the same mark is awarded to candidates of different levels of achievement. Both problems stem almost entirely from differences between LCE subjects in the percentages of candidates who take the Higher level examination and in the average marks awarded candidates.