This seemed pretty convincing to me. Please point out the flaws in the numbers.
Besides the pronounced superiority of macroeconomic performance under Democratic presidents, the fruits of economic growth are also distributed substantially more equally under Democratic presidents.
epiaction.org
The effect of a president's economic policies are not limited to that president's time in office. In fact, they usually have their main impact after they leave the office, with the exception of stimulus passed at the beginning.
So "the economy does better under Dems than Pubs" is a silly and unserious way of assessing management of the economy. Sure, it counters equally unserious people who think that the GOP is great on the economy 'cause Reagan, but it's not the truth.
For instance, Eisenhower was president for 8 years, the last two of which were a recession. Back then, recessions were less avoidable than I think they are now (it's possible that we've seen our last business cycle recession, which would have been 2000 and that was short and mild). So his tenure, which was prosperous more generally, ended with a whimper so in aggregate, the economic performance wasn't good. That, however, was just a matter of timing, not policy. So then the Dems take over and there's a boom coming out of the recession. Again, to be expected (it was like the Reagan "boom" in that regard). Then Nixon took over as the boom was nearing its end, so the economy was inevitably going to falter and the oil embargo sure as hell didn't help.
Here's how I would rate the major economic policies (at least the ones I can think of off the top of my head):
Kennedy trade liberalization = good
Infrastructure spending, Eisenhower -> Johnson = good. Infrastructure cuts, Reagan and Bush = bad
Nixon's suspension of Bretton Woods = good (though I'm not sure whether to give him credit for that; his other economic policies in response to the oil shock suggests that he threw everything at the wall and this one happened to stick).
Kennedy tax cuts = good
Reagan 1981 tax cuts = eh. Not good, but no lasting damage that I know of
Reagan 1986 tax cuts = in general good, bad in some specifics
Clinton harvesting the peace dividend and tax changes in 1993-94 = good
Bush tax cuts of 2001 = eh
Bush tax cuts of 2003 = bad
Bush deregulation of banking oversight = very very bad
Obama stimulus 2009 = good
Obamacare = good
It's a mixed record. It's not mixed after 2000. One issue where there was clear demarcation was antitrust. Since Reagan, the GOP has been wrong about antitrust and the Dems right (though it has not always been a significant focus).