Making the truth believable

Author Tracy Kidder said “I think that the nonfiction writer’s fundamental job is to make what is true believable.” I agree. In nonfiction that relies on the anecdotal stories of composite characters, I immediately distrust the expansion of “facts” to a truth about a larger universe. I need to know that the author relied on verifiable data or peer reviewed studies, and sometimes I want to see the raw data myself so I can draw my own conclusions.