Then use scenarios that actually happened. From history, business, people's personal lives, et cetera. For example: "Here is a brief description of the Byzantine Empire in 1200. The Emperor decided to change the tax policy in the following way. Predict what happened." Gives an unfair advantage to anyone who knows a lot of history (or in this case economics), but if you vary the cases enough and use little-known enough examples you might be able to control for that.

Another example: "Here's a psych profile of my friend John, and a psych profile of his girlfriend Sally. They started dating ten years ago. Predict what happened."