He is a recognized authority on the hospitality and real estate industries, for which he has conducted numerous market, economic, financial, management, and valuation studies. As a Member of the Appraisal Institute (MAI), he has appraised the market value of all types of complex income-producing properties, including hotels, resorts, casinos, vacation ownership projects, ski facilities, golf courses, and other types of hospitality properties.

He has conducted market and economic feasibility studies for hotels and resorts in the United States, Europe, the Pacific, and Asia, including master-plan studies for multi-use real estate projects in the U.S., Singapore, and the Republic of China.

A graduate of Washington State University, Callahan is a Certified Public Accountant (CPA), a Certified General Real Estate Appraiser, and a Fellow of the Royal Institution of Chartered Surveyors (FRICS). He is certified as an expert witness in his field in both State and Federal Courts in New York, Massachusetts, Illinois, New Mexico, Texas, Washington, Oregon, Nevada, Arizona and California.

Mr. Callahan is a frequent speaker at industry conferences and is regularly quoted in industry publications and in the general press. He is a member of the International Society of Hospitality Consultants (ISHC) and the Counselors of Real Estate (CRE).