The Problem with Audience Participation

James Taranto reports this recent interchange, during which economist Paul Krugman tries to make the case for a Canadian-style national health care system:

Krugman: --and I wanted to ask, actually two questions, to the audience. First, how many Canadians, would Canadians in the room please raise your hands. [One person applauds, laughter]

Donvan: We have about seven hands going up—

Krugman: OK, not as many as I thought. OK, of those of you who are not on the panel who are Canadians, how many of you think you have a terrible health care system. [pause] One, two--

Donvan: We see—almost all of the same hands going up. [laughter]

Krugman: Bad move on my part.