4. The kind of person the author is

He is very scholarly and data based person.  He is a economist and it shows in the book with all of the figures and statistics packed inside.  The author knows what he is talking about and that you can trust him on the subject matters he puts into his book. By all of the data he collected that is in the book, it can be reasonable suspected that he did his research and traveled around to get the answers to his proposals and make sure Levitt had them right and usable in his book.