I recently faced a similar question. My response was that I would need more detailed information about the position. At this point in the interview they had not clearly defined the role I would be placed into. Instead they were trying to see how I might fit their organization. I explained that what had been described thus far could be a simple junior position, or it could be a senior customer facing position. The range for those roles is quite large and my skills/experience do not warrant a junior role. So picking a spot for what amounts to an unknown would not benefit anyone. They said they understood and moved on.