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Digital Education team blog


Ideas and reflections from UCL's Digital Education team


Certainty Based Marking Webinar

By , on 6 April 2011

Emeritus Professor Tony Gardner-Medwin gave a Webinar presentation on Wednesday 6th April about using Certainty Based Marking (CBM) for both formative self-tests and summative e-exams.

This type of assessment helps students to understand what areas of a topic they really do know and what areas they need to work on by asking them to choose, on a 3 point scale, how confident they are that their answer is correct.

Questions they answer correctly and with high certainty score the most points, while those they answer correctly with low certainty score fewer points. Questions they get wrong are negatively marked in a similar fashion.

The scoring method is best demonstrated in the following table:

Certainty level No reply C=1 C=2 C=3
Mark if correct 0 1 2 3
Penalty if incorrect (T/F Q) 0 0 -2 -6

When used formatively, students can review their marks and focus on reviewing the material where they were either unsure of an answer or confident of their answer, but incorrect.

Certainty Based Marking can also be used for exams. Evidence has shown that exam results evaluated using CBM closely matches ( tending to be slightly higher) than the scores the students would have received if traditional incorrect/correct marking were used. This can be easily compared, because each CBM exam result can be marked in both ways.

Find out more about Certainty Based Marking here: http://www.ucl.ac.uk/lapt

The CBM Webinar presentation will shortly be available here: http://transformingassessment.com

UPDATE: The Webinar and related materials are now available from here: http://www.ucl.ac.uk/~ucgbarg/pubteach.htm

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