Can You Really Predict the Success of a Marriage in 15 Minutes?

from Slate:
The upshot? What Gottman did wasn't really a prediction of the future but a formula built after the couples' outcomes were already known. This isn't to say that developing such formulas isn't a valuable—indeed, a critical—first step in being able to make a prediction.

The next step, however—one absolutely required by the scientific method—is to apply your equation to a fresh sample to see whether it actually works. That is especially necessary with small data slices (such as 57 couples), because patterns that appear important are more likely to be mere flukes.

But Gottman never did that. Each paper he's published heralding so-called predictions is based on a new equation created after the fact by a computer model.