I would like to discuss the way how Gradebook in 1.9 deals with scales when I choose the display type to "percent". This is my use case:
I have created a custom scale "Solution quality" with the following scale items:
* weak solution ** has some drawbacks *** that might work **** perfect solutionIn the grader, I have set the item using this scale to display grades as "percent". I was surprised that the grader reported strange values. E.g. a student received ** out of **** which is something I would consider as 50% grade. But actually he received only 33.33%
.The reason is the grader considers the scale as an item with minimal grade 1 and maximal grade 4. These values are mapped to percentual values as follows:
* = 1 = 0% ** = 2 = 33.33% *** = 3 = 66.67% **** = 4 = 100%I.e. the percentual value is calculated as (2-1)/(4-1) = 1/3 = 33.33%.
But in this case, the * should represent 25% and no grade should mean 0%. The solution for me might be to extend the scale so the worst level is "wrong solution" or so.
As this is not very intuitive for me, I want to ask if this is really expected behaviour for the others or we might consider this as a bug.
TIA
. This is something that should be explained in the docs clearly; maybe in the tutorial as another case?