"Truth" and "fact" may mean different things to a journalist, an academic, and a lawyer. Any way you slice them, they can be remarkably elusive. I've personally interviewed multiple eyewitnesses to events and come away with dramatically different versions from each one. I've talked to other eyewitnesses to events I've witnessed and realized that were radical differences between what they saw and what I saw. I've witnessed events at close range that were both widely reported and eminently reportable (occurring in a brief time in a confined and easily accessible location) and come away convinced that the accepted record of those events is in many ways wrong. Or possibly it's my memory or powers of observation that are astray, though I've no cause to doubt either.

None of that is meant to suggest that we should stop looking for truth and for facts, or that avoiding or circumventing obvious evidence or necessary procedures is acceptable. It just means that even when all the pieces seem in place and all the approved processes have been followed, a fair degree of skepticism is required.

New Yorker's fact checking method, as they admit in multiple places, involved speaking to no witnesses or named indigenous people. The editor said "in this case we consulted a large number of experts in the various fields the material touches on.” In other words, no specific facts were checked
This does not surprise me at all, and it's not uncommon. One of my favorite recent cases is the one discussed in this thread:

http://council.smallwarsjournal.com/...ead.php?t=2165

Again, prominent author, prominent publication, absolute load of bollocks. Of course if you didn't happen to know something about the subject, you wouldn't notice... which makes me wonder if that sort of standard is the norm. If they get it that far wrong when they write about things I know about, why should I trust them on things I know less about?

it's no mystery IMO what studies have credibility. There are signposts like transparency of method and providing clear sources and documentation.
True, though of course works like Diamond's hardly qualify as "studies" in any academic sense. Still one finds studies that appear to be credible, and on further examination they turn out to be far from it. All you can do is work from as many sources as possible, both journalistic and academic, spend as much time in the field as possible... and still retain the awareness that there are perspectives you haven't heard and parts of the story you haven't seen.

Makes it rough on people who are paid to come up with conclusions, but that's way it is...