Complexity. In general individual decision makers must be assumed to have multidimensional values which attach nonmonetary subjective cost or value t… - Vernon L. Smith

Economics as currently learned and taught in graduate school and practiced afterward is more theory-intensive and less observation-intensive than perhaps any other science. I think the statement that "no mere fact ever was a match in economics for a consistent theory" accurately describes the prevailing attitude in the profession (Milgrom and Roberts, 1987, p. 185).

One of the most intriguing discoveries of experimental economics is that (1) as we have seen, people invariably behave non-cooperatively in small and large group ‘impersonal’ market exchange institutions; (2) many (up to half in single play; over 90% in repeat play) cooperate in ‘personal’ exchange (two-person extensive form games); (3) yet in both economic environments all interactions are between anonymous players.

When the theory performs well you also think, “Are there parallel results in naturally occurring field data?” You look for coherence across different data sets because theories are not specific to particular data sources. Such extensions are important because theories often make specific assumptions about information and institutions which can be controlled in the laboratory, but which may not accurately represent field data generating situations. Testing theories on the domain of their assumptions is sterile unless it is part of a research program concerned with extending the domain of applications of theory to field environments