During FiveThirtyEight’s tenure with The New York Times, Mr. Krugman referred to FiveThirtyEight or to Nate Silver 21 times. Over all, 15 of these references were favorable, as compared to five neutral references and one unfavorable one.

But Mr. Krugman’s views of FiveThirtyEight have changed since it re-launched March 17 under the auspices of ESPN. The columnist has mentioned FiveThirtyEight four times in just nine days, all in negative contexts. (Mr. Silver has frequently criticized what he calls “pundits” and “opinion journalists,” including those who write for The Times.)…

While it can be easy to extrapolate a spurious trend from a limited number of data points, the differences are highly statistically significant. At his current pace, Mr. Krugman will write 425 more blog posts about FiveThirtyEight between now and the 2016 presidential election.