Maybe try not calling it 'market index'. This is a familiar (sounding) term to most people, so they will assume they know what it means, and wont look for an alternative definition.

Since it is an original metric that you have created, why not give it an original name? Even better if you can link that name to your company name, think 'Zestimate' from Zillow - easy to say, obviously a 'new term' so something that I need to learn, and feels like it belongs to the company, due to the 'Z'

All that said, I'm still not quite sure what real world problem this site solves..