There's a time lag between policies and the economy's reaction to them. This article looks at a one year lag. I think it's even longer. One can call it "massaging" the numbers if they don't like the results. But it should makes sense even those who don't study the Economy.

"If you buy the 1-year-lag theory, something even more interesting pops out of the data. In looking at the trend over the last year of each term (the right-most column in the previous table), we see that every time an administration changed from Democrat to Republican, the trend was negative. That is, the Democrat left a decelerating economy for the Republican. Every single time: Truman to Eisenhower, LBJ to Nixon, Carter to Reagan, and Clinton to Bush 43.

Conversely, every time an administration changed from Republican to Democrat, the trend was positive. That is, the Republican left an accelerating economy for the Democrat. Every single time: Eisenhower to JFK, Ford to Carter, and Bush 41 to Clinton."