Abstract
This paper presents a method for the computer modeling and encoding of clinical causal relationships (CR's). This method draws on the theory of multivariate linear models and path analysis. The representation was used to encode medical CR's derived empirically from a clinical database by the RX computer project described in SCAMC82. The emphasis in the representation is on capturing the intensities of effects and the variation in the effects across a patient population. This information is used by RX in determining the validity of other CR's. The representation uses a directed graph formalism in which the nodes are frames and the arcs contain seven descriptive features of individual CR's: intensity, distribution, direction, mathematical form, setting, validity, and evidence. Because natural systems (such as the human body) are inherently probabilistic, linear models are useful in representing causal flow in them.