Let's say a student takes multiple different tests. I get a percentage for each of the test scores (the tests have a different amount of multiple choice questions, and the multiple choice questions are all different across tests).
What level of measurement can I use to compare these different percentages? Is it ordinal, interval or ratio?
This other post Measurement level of percentile scores suggests that it should be interval. However, my question is different as there are different "questionnaires".
Does having different sources for the percentages affect anything?
