Third, Kushner suggests, the causal link between process and outcome is typically interrupted by so many intervening variables as to make it unreliable. In the SCR evaluation, we documented 56 such variables—including training, permissions, physical space, technical interoperability, local policies and protocols, professional sanction, and point-of-care consent
http://plosmedicine.org/article/info:doi/10.1371/journal.pmed.1000360#article1.body1.sec2.p6

Presumably this issue only applies to some kinds of goals. For example the goal previously mentioned of providing access to summary care data from the patient's home is pretty easy to evaluate cause and effect for? Obviously then harder to evaluate how that access might affect patient health.

In any case, some of the example variables mentioned for the SCR might be seen to be 'part' of the SCR - as key aspects of the context of use to be designed for, or things that could be influenced by stakeholders of the SCR.