It is really helpful. Your ability to justify your sample size and technique will be highly rewarded here.
Would you have discovered anything else if you had used a different approach? To answer this question, you need to know every detail of your research project from chapters one to the end. What are the limitations you have faced while writing? Who will be interested in your research?
This question can be very tricky and it goes a long way in convincing your panel members that your study is worth their time. I am using it to prepare my viva. To answer this question, you may decide to elaborate on the problem investigated in the study.
Knowing common thesis defense questions and answers is vital to passing your defense as you will be expected to do far more than just give a brief presentation.
Question 1: In few sentences, can you tell us what your study is all about?