For stories that appeared in the Times or Times blogs through July 2013, Carson was referred to as “Dr.” on either first or second reference 29.6 percent of the time. Jill Biden has been referred to as “Dr.” on either first or second reference 35.3 percent of the time.

That’s despite the fact that Carson, who first graced the pages of The New York Times in a September 1987 story about his successful separation of Siamese twins, would spend at least the next 25 years of his public life known only as a doctor, with no political profile at all.

Finally, I would like to add two other factors that I think likely have some explanatory power: First, many Times writers, knowing only that Biden is somehow involved in breast-cancer issues, likely have the mistaken belief that she really is a medical doctor, and have just never bothered to investigate the matter. Second, many Times editors are, quite frankly, just pretty crappy about remembering and enforcing their own house rules.