Evaluation and Research in Education
Editor: Professor Keith Morrison, Inter-University Institute of Macau
Associate Editor: Professor Stephen Gorard, University of York
Statistical Adviser: Professor Colin Baker, University of Wales Bangor
Reviews Editor: Dr. Emma Smith, University of York
|
Volume: 15 Number: 2 Page: 95–107
|
|
|
|
|
The Question Tariff Problem in GCSE Mathematics
|
|
Tom Bramley
|
|
In GCSE mathematics there are many question parts (items) worth 2 or 3 marks. The mark distribution in some of these items is U-shaped - for example in a 2-mark item where the majority of candidates score
either 2 or 0. Such items are effectively single-mark items being given double weight. This contributes to the spread of raw scores and therefore makes the test appear to be more discriminating than perhaps
it is. The source of the problem is in the design of the mark scheme, which has to allocate the marks to fit a tight specification of content coverage and ability targeting. After identifying such items,
analysis of their mark schemes showed that the most common causes are awarding an intermediate mark for correct working, and awarding marks for repetition of a single process. The items were re-scored to
remove under-used middle categories. Several comparisons with the original scores, including a simulation of test scores, showed that the amount of measurement error was reduced and hence the quality of
the examination was improved.
© Multilingual Matters 2001
Full text PDF
|
