Certainty-Based Marking (CBM) and Moodle
Certainty-Based Marking (CBM: see LAPT) was devised to reward students for distinguishing between uncertain and reliable answers. It enhances student reflection and assessment reliability. The best way to use CBM with Moodle quizzes is EITHER to use Moodle 2.6 with the plugin for CBM grade reports, OR to install the patches below for earlier versions. See also Using CBM in Moodle Documents.
Specific Features available for Moodle versions
Downloads. Click the link here to download code patches for Moodle versions before 2.6. These don't affect database structures, or functionality when CBM behaviour isn't selected. Installation is easily reversed if you wish, by copying in the folder containing the original versions of the files that are changed. There is a forum for any discussion, suggestions or report of problems.
- Moodle 1.9-2.0: There is no CBM behaviour in standard Moodle code. Good CBM behaviour is available with replacement of a few files with versions available to download below. Weights assigned to individual Qs are ignored with CBM behaviour, so all Qs give 1, 2, or 3 marks if correct at C=1,2,3. A 'No Idea' option is included (mark=0) so students don't have to guess to see feedback if they have no idea. Submission of answers is with a single click. Percentage scores are optionally shown relative to the questions attempted. Attempt reports only give feedback for Qs the student has attempted. A 'Knowledge' score is included, which is accuracy scaled so pure guesses (at C=1) would give on average 0%.
- Moodle 2.1: Basic CBM behaviour was implemented in standard Moodle code, but CBM users are advised to upgrade from this version.
- Moodle 2.2-2.5: Default basic CBM behaviour in Moodle gives marks 0.33, 0.67, or 1 for C=1,2,3 unless weights are all changed to 3. This is changed with patches to marks 1,2,3. A 'No Idea' option is implemented with the patches. Feedback with patches includes both accuracy and CBM scores, with breakdown of performance by C level - as with the patches for Moodle 1.9+, but not in core Moodle till 2.6.
- Moodle 2.6: CBM behaviour now works well for students in core 2.6. Default weighting of Qs gives marks 1,2,3 for C=1,2,3. CBM Grade Reports for teachers require installation of a PLUGIN, from the Moodle site, or from here. Limitations: The 'No Idea' option is not currently available; attempt reports show feedback for all Qs, even when the student has not attempted them; Q submission always requires 2 clicks (C, then 'Check') rather than 1; 'Knowledge' scores (corrected for average accuracy with guessing) are not currently available.
Demonstration Sites: These are demo sites to show what effects the patches for older Moodle versions will have
(1) with Moodle 2.4 Dec 2012. Login as a 'test student' with username = 'moodler', password = 'moodler' . Email me for access as a teacher.
(2) with Moodle 2.2 (Moodle 2.3 available code is similar). Login as a 'test student' with username = 'moodler', password = 'moodler'. Email me for access as a teacher.
(3) with Moodle 1.9.
Login as a 'test student' with username = 'moodler', password = 'moodler', or register in your own name and ask to have the role of 'teacher' (further instructions on each site).
CBM in LAPT (London Agreed Protocol for Teaching)
LAPT (www.ucl.ac.uk/lapt is software developed by me at University College London (UCL) for student self-tests with CBM. In many respects it is more efficient and easier to use for this purpose than Moodle, and is freely available for use by other institutions. It presents scores as "Accuracy", "Knowledge" (corrected for guessing), with and without the "CBM Bonus" for good discrimination.
Links to discussions about CBM on the Moodle Forum and elsewhere
Marks, accuracy and CBM 2013
Certainty Based Marking in Moodle (Isabelle Langeveld's blog) 2011
Quiz Report Averages 2011
Testing CBM 2011
Tony Gardner-Medwin (UCL)
Revised December 2013