A heuristic evaluation typically employs three main approaches;

  1. Provide evaluators with a set of tasks to be carried out
  2. Provide system goal’s and let evaluators develop their own tasks
  3. Let evaluators assess dialogue elements

I understand that choosing the right approach depends on time constraints and the maturity of the system. So for instance if the system is a functioning product then the first approach shall be used, the second approach is for early stages, alpha, beta...  But i don't understand the third approach can somebody please explain?