The iterative process of "differential diagnosis" (DD) seems to follow the SM (see below). There are descriptions of DD that suggest that the process uses the process of elimination in order to arrive at a diagnosis. Again, this is one outcome of the application of this methodology. With well defined symptoms for the characteristics of a diagnosis, it is quite likely that this outcome may represent the majority of outcomes. But what if there are two diagnosis with the same presenting symptoms and no further methods to test these two hypotheses in order to discriminate between the two?

The descriptions of DD seem to include the same characterizations of the process that we are discussing here. It is a process of "falsification" and not a process of elimination.

In addition, the real questions is how do you reliably know what should be there? That is why a "closed system" is not a scientifically reliable construct in fire investigation.


“Differential diagnosis” is an iterative process (within the hypothetico-deductive model) with four steps designed to establish a particular patient’s clinical diagnosis—(1) listening to the patient describe symptoms and observing signs, (2) generating from those observations hypotheses about a process of disease or symptom formation, (3) gathering additional data to test these hypotheses, and (4) evaluating these hypotheses in light of these data. These four steps are repeated as many times as hypotheses are considered and then rejected, confirmed or set aside for further testing. D. L. Sackett et. al. Clinical Epidemiology, p. 17 (1991); H.C. Sox, et. al. Medical Decision Making, pps. 9-26 (1988); J.P. Kassirer. Diagnostic Reasoning. Annals of Internal Medicine, 110:893 (1989); R.L. Engle, Jr. & B.J. Davis. Medical Diagnosis: Past, Present and Future. Archives of Internal Medicine, 112: 512-543 (1963); F.J. McCartney. Diagnostic Logic. BMJ, 295: 1325-1331 (1987); J.P. Kassirer & R.I. Kopleman. Learning Clinical Reasoning, pps. 109-114 (1991).




Mark Goodson Wrote:
-------------------------------------------------------
> The MDs refer to it as DD, or Differential
> Diagnosis. A well established tool used for
> sorting out what ails one.
>
>
>
> For a TRUE "process of elimination"example
>
> A 2 year old presents without ever having had a
> dirty diaper.
>
> No bleeding - rule out Meckel's diverticulum, even
> though it is congenital
>
> Toxicology screening negative - No drug use by Mom
> or reaction to delivery drugs which may slow down
> the peristalsis of the gut
>
> Suction biopsy performed - few to no nerve cells
> (hypoganglionic or aganglionic) - kid has
> Hirschsprung disease...
>
>
> In the above example, two conditions were ruled
> out by testing, while the third condition
> (Hirschsprung) was indicated by the DD, and
> confirmed by the biopsy.
>
>
> As applied to a fire, POE usually (in my mind)
> would deal with a closed set - we KNOW what should
> be present - (TV Stereo Stove Toaster and can
> opener) However, if there is some outlier there,
> then issues can arise - the so called bird with a
> cigarette or a squirrel with its tail on fire.

Douglas J. Carpenter, MScFPE, CFEI, PE, FSFPE
Vice President & Principal Engineer
Combustion Science & Engineering, Inc.
8940 Old Annapolis Road, Suite L
Columbia, MD 21045
(410) 884-3266
(410) 884-3267 (fax)
www.csefire.com