I am working on a framework to evaluate our products usability against our product design tenets which are nothing else than 10 usability (N&N) heuristics in our own words. The goal is to identify which of the usability areas we're not doing great. That said, we have 8 heuristics covering specific usability areas. There will be a checklist in each of the heuristics to be scored against and at the end we will have a percentage as the score for each one.
My question is, how do you know what each score means? Is 70% good or bad? How do I set the threshold? Also, how do you weight each of the heuristics in order of importance? Surely it's more important for a website to, i.e., always provide system feedback and in a timely fashion rather than for it to be pretty looking.
I wonder if you have any advice? I hope all this makes sense. Thank you