Not a lot to talk about lately - have been working on development of the inference rules for determining what I will call the “minimal abduction set.” The minimal abduction set will be similar to the “minimal adjustment set” for inductive reasoning through a casual structure to determine what information you need to know for the induction to avoid bias and confounding. But, the minimal abduction set will be for abduction, rules to determine, based on a causal structure, the minimal set of information for abducting a cause from an observed effect. It will be helpful for the generation of clinical prediction rules and for reasoning through diagnostic and prognostic reliability.
But I was reminded this week of how our practice knowlegde when developed through clinical experiences alone are bound by the reality and limitations of our place in space and time. This reminded me of why we do need methodological structure to our observations for which we inductively generate knowledge and causal models, or at least a solid framework for considering the limitations of our naturally occurring observations. The design of an experiment or epidemiological study where we will systematically observe reality (either manipulated or not manipulated) requires us to consider the points of selection and how those points of selection influence the sample we end up observing. In practice we exist in a structure, a certain place, that has points of selection that we may not consider.
For example. After presenting about ECG abnormalities I was asked a question by a practicing physical therapist. The question was: what is the big deal with complete AV heart block? Why do people act like it is a life threatening issue? I asked the PT where they worked (acute care hospital), and why they believed complete AV heart block was non life threatening. The answer was that they see people all the time that were at home feeling unsettled for a day or longer, finally came to the ER, were found to be in complete AV heart block, were admitted, had a pacemaker implanted and were just fine and dandy. Therefore, they concluded, complete AV heart block is non life threatening.
What is the problem with this conclusion based on these observations?