When data are collected in a survey (an observational study), relationships between the variables may be observed, but it is difficult to conclude that either variable causally affects the other. On the other hand, data that are collected in well-designed experiments do give information about causal relationships.

Experiments are less common in business than in the sciences, so this version of CAST contains fewer sections about experimental design than the General or Biometric versions.

To learn more about experimental design after studying this chapter, look at the General or Biometric versions of CAST.