You're approaching it from the standpoint that it's an exact science, but it's more of a social science and you can't really pin down exact specifics, but only best guesses. Unfortunately (and I fell into this camp for a long time) many people see economics and see the mathematical models and assume that it must be scientific or precise, but the marketing campaign to legitimize economics unfortunately confused many of us into that misconception.
It's helpful to think of economics as a field under the branch of political science, which itself isn't very scientific.
I like to think of it as not really one or the other, but as both. It’s like a venn-diagram intersection of finance and sociology. Some elements of economics are purely quantifiable, and some elements are purely human.
It's helpful to think of economics as a field under the branch of political science, which itself isn't very scientific.