Remember: all dissertations must be limited in scope. I have seen so many overly complex designs with too many research questions and too many components. Unfortunately, the committee may not remind you that you’ve taken on too much and that the chances of completion are low. It is your job to limit your study.

If it’s too simplistic, it’s probable that the chairperson or committee member will ask you to add another component to the study, but if it starts out being just too gigantic or overwhelming, they may indeed approve it. Now what? You are stuck with carrying out this somewhat impossible task of collecting massive amounts of data.
Don’t choose a sweeping dissertation topic; instead, choose a narrower topic so that you can keep your focus. This approach will increase the possibility of completing your dissertation sooner.