 The program described in this section did much to illuminate the relationship between causation and probability. In particular, it helped us to better understand the way in which causal structure can give rise to probabilistic relations of screening off. However, despite the mathematical framework of the program, and points of contact with statistics and experimental methodology, this program did not give rise to any new computational tools, or suggest any new methods for detecting causal relationships. For this reason, the program has largely been supplanted by the causal modeling tools described in the next section.