For competency interviews, a useful approach for structuring your answer is the “S-T-A-R” technique:
Situation
- Tell us about a time when you displayed [x-competency]
Task
- What needed to be accomplished? What was done?
Action
- What did YOU actually do?
- What was your role on that committee?
Result
- What was the outcome?
- How did your own actions contribute to that outcome?
