Committees rarely fail a candidate for choosing the 'wrong' test. They raise concerns when a candidate cannot explain why a test was chosen, what its assumptions were, and what would change if those assumptions did not hold.
Before a defense, it helps to walk back through the analysis plan and be able to state, in plain language, why each statistical decision was made and what it means for the conclusions drawn.
A short review session with a biostatistician can turn a technically correct analysis into one the candidate can confidently defend.
