How to objectively determine CAP rates in a market / sub-market?

[Jeff Owen]

Is there an objective resource to use to determine the CAP rate for a commercial multi-family property? I want to be armed with better information than just what the seller's agent is providing me. I'm not finding a lot of tools that I can use, and even looking at recent sales may not give me enough info to back into the CAP rate unless I happened to also have the P&L info for the property.

Your thoughts are greatly appreciated!