@hamje32 - I think that economics is part art, part science. Quantifying inputs and outputs is the science part; the art part is recognizing that there are things outside your control.
I vaguely recall from my college economics class hearing about something called an economics multiplier, to measure how changes in outside events affect the model.
In other words, there are things they don’t know which could turn any model on its head.
That’s why you get different answers from economists about economic projections. They’re all trying to predict what those outside variables will be and how they will impact their models.