Look, this is a news release. It's about as pure a form of rhetoric, as completely style-over-substance, as is imaginable. But it's hard to let that comment slide.
The economic data to which McConnell refers is probably threefold: decreasing unemployment, increasing employment and the spike in gross domestic product in the most recent quarter. So, breaking that out:
All good news. And, in McConnell's phrasing, it "appears to coincide" with "the expectation of a new Republican Congress."
"Appears to coincide" is a nifty little phrase. It suggests that we need an addendum to the hackneyed (but true) "correlation doesn't equal causation" line: "Correlation doesn't equal causation, and two things happening in the same general vicinity doesn't even equal correlation." Here are the long-term trends in unemployment, jobs and GDP, with the period in which it seemed obvious that the Republicans would win control of the Senate indicated.* That's mid-September to Election Day.
Unemployment looks like this. The most recent data is through November.
Employment looks like this. Data is over the same period.
You'll notice that the tail end of each graph is simply a continuation of the months that precede it. One assumes that McConnell doesn't think that people's expectations of a Republican Congress in 2015 began in 2011, presumably.
So what about GDP?
GDP was the really big news recently. Five percent growth quarter over quarter is big. But the most recent data is for the third quarter of 2014, which is to say, the quarter ending in September. Is McConnell suggesting that the economy picked up because people in July were doing more shopping with the expectation that he was going to be the next majority leader? In July, SurveyUSA had McConnell up by only two points!
We get it. This is politics. But the tendency in politics to cherry-pick cause and effect is so completely over the top by both parties and their leaders that it's worth calling out from time to time. There was definitely a boost in spending and employment as a result of last year's elections, particularly in the political campaign, TV advertising, and Hill staff sectors of the economy. Otherwise, it is safe/smart/obvious to assume that whatever effect an all-Republican Congress might have on the country's economy has not yet shown its face.
* Evaluated as "everything after the point at which Democratic odds of retaking the Senate peaked at 538."