Ian at Truck and Barter digs up a definition coined by Edward Tufte. It's not a compliment.
economisting: (e kon' o mist' ing) 1. The act or process of converting limited evidence into grand claims by means of rhetorical ploys, especially punning. 2. The belief or practice that empirical evidence can only confirm and never disconfirm a favored theory. 3. Conclusions that are theory-driven, not evidence based. See also confirmation bias, painting with a broad brush, Iraqi weapons of mass destruction, post-modern critical theory, marketing.
That's just not nice.