I would focus on a success story of how you have used data with a past client or past project. Remember the interviewer is trying to get into your brain and wants to know how you process and use the data to showcase the strategies that you have suggested.

As a strategist, you would definitely want to avoid suggesting that you don't need to use data to back up your strategy. If the interviewer is asking this question they probably think it's an important part of the role that you applied for.

"Data has always played a large part in developing my brand strategy. I like to work closely with the research team to help them consider the best research data to gather so we can provide the clients with the best options. Once the data is gathered then I meet with the research team to review all of the information and formulate a couple of strategy options. In my recent project (explain a recent project where research was used successfully)."