WSJ article today showed stock market growth with
Rep pres & Dem Congress 10% (or less)
Dem pres & Rep Congress 13%
Rep pres & Rep Congress 17%
it also refuted the line that “the economy does better when democrats are in charge”.
Put Kennedy (supply sider) in the Rep column, Nixon (regulator) and G HW Bush (tax raiser) in the Dem column, and the data reverse substantially. Heck, even remove the single data point of Nixon and the trend that they claim for Dems collapses. Not much of a study if the removal of a single datapoint destroys your conclusion.
Nixon had price controls and JFK had tax cuts. Those studies should be controlled for actual policies.