OK, is there an objective, reliable way of determining the FACTORS that causes an economy to do well or turn sour?
I do know this -- the stock market already started going up under Obama, but it REALLY TOOK OFF after Trump got elected. I also know that the unemployment rate was trending downwards under Obama and went down even further after Trump took office. so, there is a basis for saying that the economy was already trending positive under Obama. In what way then can we attribute the positive economic news today to Trump's policies?
I really want to know because we can go back and forth as to WHEN the economy really did well but without these objective methods, we cannot really know whose policies actually worked.
Absolutely not (and I say that as a guy with an Econ degree, as well as real science degrees). The economy is just too complex. There are about an infinite number of moving parts, and some of them take years for their effects to be "seen". [Also, the POTUS controls pretty much none of them].
The stock market, which is not a good economic indicator in normal times and is completely disconnected from reality and has been for several years, went on an absolute tear during 0's reign. It tripled, and IIRC experienced the longest bull market in history. Then, at least at first, when DJT was elected it started growing even faster. Take your pick.
Now, if I were looking for CLUES as to how the economy was reacting to policies, I'd look at things like consumer confidence surveys, Purchasing Managers' Index, and levels of capital investment. If people are planning on buying more stuff and companies are investing in the capability to make more stuff, I'd say that's a pretty good indication that things are heading in the right direction. It is in no way perfect. We've had a very long, slow "recovery". At some point, people could be buying more stuff not because they are confident about their future, but because they put off those purchases during the long period of uncertainty and now they simply can't put them off any longer [not saying this is true, but it's possible]. And any new confidence could be caused by any number of unrelated issues. But if I was trying to find a connection between POTUS and the economy, that's where I'd be looking.