How Do You Quantify Social Media?

I am always taken aback when people ask how I quantify how much business revenue using social media has translated into for a company.

Social media is a relationship-building endeavor. It's being willing to put yourself out there in public on the Internet and interact with potential customers/clients while sharing worthwhile information.

Can you quantify how many times a person/company interacts with you before buying your product or service?

A comparable question might be:

Can you...