Suppose that you were to send out the text of this question to two friends, and both of them comment on your final two sentences.
Friend A writes: "The sentences are grammatically correct, although they might be better posed as a single question instead of two, by writing 'feedback, or' instead of 'feedback? Or'".
Friend B writes: "It is unclear how these questions connect to what came before. I don't understand to what 'the measure' refers; there was no talk of any measure earlier in the question. Similarly, it is unclear to me how you would average feedback. Please clarify these concepts."
Now, I think you are asking the wrong questions here. Both friends give you qualitative feedback. Maybe the one is being too harsh, maybe the other focuses only on particular aspects (in my example, Friend A seems to focus mostly on whether sentences function well internally, while Friend B focuses on how sentences interact with the overall text). The point is that you can learn more by asking for multiple opinions, and all opinions you receive might contain something useful. It is counterproductive to try to quantify how qualified a reader is. Instead, get a blend of opinions. Use the ones that are useful to you. Next time, ask for feedback again from the persons who gave you useful feedback before, and switch out the people who gave you useless feedback for new people.