What was the control in Eddington?

* https://en.wikipedia.org/wiki/Eddington_experiment

Einstein's models made a prediction, people tested/measured that prediction, it turned out true/accurate. General theory has made other predictions, and empirical observations have found them to be accurate as well.

A phenomena was going to happen (e.g., tax law changes): some economic models predicted X would happen, and some predicted Y would. We can see which were more accurate.

Plenty of "real" science is/was done outside of controlled experiments.