Suppose a Case Management Program Is Established to Reduce Rehospitalization

Multiple Choice

Suppose a case management program is established to reduce rehospitalization rates in a hospital and that those rates drop dramatically once the new program is established. We can conclude that:​

A) ​research has demonstrated an effective approach to practice.
B) causality cannot be inferred because time order was not established.​
C) another event occurring during the time of the study might explain away the change.​
D) the absence of covariation threatens the internal validity of any causal inferences.​