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numbas / Numbas

A completely browser-based e-assessment/e-learning system, with an emphasis on mathematics
http://www.numbas.org.uk
Apache License 2.0
199 stars 118 forks source link

"Allow negative marking" statement for marking algorithms #713

Open christianp opened 3 years ago

christianp commented 3 years ago

At the moment, Numbas applies a hard lower limit of zero credit to parts after submission has finished.

Some marking schemes, such as confidence based marking, require negative marking. The idea is that submitting a wrong answer is worse than saying nothing at all.

There could be an "allow negative marking" statement in a marking algorithm (it could just be a note called something like allow_negative_marking, taking a boolean value) to stop this limit being applied.

If this was a generic part option in the editor, it would both clutter the interface and make it hard to implement a reusable custom part type which always does negative marking.

christianp commented 1 year ago

Now that there are a few special notes in marking algorithms, I'm not keen on adding more. This should really be a straightforward checkbox option. Custom part types could have the same checkbox; I don't know why I thought that was an obstacle!

christianp commented 1 year ago

The next question is: where should this option be, and when should it be available? It might make sense for "allow negative marking" to always be visible in a MCQ part, because you can easily set negative marks for the options. But in a number entry part, you'd have to make a custom marking algorithm for it to be possible to award negative marks.