I thought there was one time in the early industrial age (sorry, no save available, will try to reproduce) that I tried producing research, and it upped my science output reasonably well...but when I tried producing wealth, it upped my science output even more. I don't recall adjusting the slider, but I probably did. Since then, I have found other occasions.
So, my guess at what happens may be wrong, but the ultimate guideline is not... if you need research, be sure to check out building wealth before you commit to building research; you may be able to kill 2 birds with 1 stone.