I have used and/or adapted several questionnaires for my dissertation study. I have already asked the authors for permission to use their scales. However, I have not received a reply from an author about using his scale.
I wonder if we have to have the permission of the authors when we use their surveys (when the questionnaire items are published and publicly available), or is it a courtesy to ask for the permission. Is it still okay to use a public scale when no confirmation is received from the author who developed the scale?
Thanks for any suggestions!