Q: If a property was owned by a publicly traded company, would actual cap rates and operating expenses be available?
A: In general, information from publicly traded companies is more robust because of reporting requirements. But it seems highly unlikely that a publicly traded company would provide such detailed information as the actual NOI at the time of a sale – or offer information that could be used to identify it.
Q: If all expenses and rental incomes are estimates in an appraisal, why in some instances do appraisers request additional historical data when making their analysis? Are they making projections from the historical data?
A: It's a very good sign when an appraiser requests and, presumably uses, historical data in arriving at a stabilized set of rental incomes and rental expenses. He or she is very likely doing precisely what you suggest, i.e., using the very best historical information available in arriving at estimate of stabilized NOI.
Course overview: The Appraisal Report and Approaches to Market Value