How validity travelled to economic experimenting

Validity was first given a more specifically scientific meaning by psychologists in the early twentieth century in the contexts of psychological tests. Following the classification of different validity-types in the American Psychological Association's Technical Recommendations (1954), validity travelled from psychological tests to psychological experiments through the work of Donald Campbell. Thus the idea was introduced that also experiments could be more or less valid. In addition, a distinction was made between the internal and the external validity of an experiment. Of the two domains in which validity was employed in psychology, only the internal and external validity of experimental methodology travelled to economics. The initial implementation of validity in economic experimentation was reluctant, and focused upon showing how external validity in particular was not problematic in economic experiments. However, the gradual adoption of validity by economists working with experiments eventually led to the clear, analytical definition of internal validity by Francesco Guala, a definition that was subsequently taken over by other economists. In its travels from psychological tests to psychological experiments to economic experiments the concept of validity generally retained its meaning as the accuracy of a scientific procedure. At the same time, however, it was put to use in dissimilar ways and elicited different discussions in the scientific realms in which it was applied.