Re: Evidence

Daniel Rubin wrote:
> 
> At 07:15 AM 6/11/2007, Matt Williams wrote:
> 
>> I changed the subject line to make it more specific.
>>
>> I think that Evidence is a tricky, slippery subject. It seems to be 
>> both traces (i.e. records of something) and in many cases, inferences. 
>> Those inferences probably shouldn't be called evidence, but they are 
>> the reason that some data are considered evidence, and others not, and 
>> hence often get included.
> 
> Actually, sometimes the interpretation *is* part of the evidence--best 
> example is medical imaging wherein the radiologist interpretation of the 
> images are part of the primary evidence (the image is the "raw" 
> evidence, but you have no result without the radiology interpretation of 
> the image).

I'd think of the image as of a piece of evidence (of whatever the 
patient may suffer from), and the radiologist's interpretation (a 
written or spoken statement thereof) as another piece of evidence (of 
that the radiologist must have judged the image as a piece of evidence 
for whatever the patient may suffer from).  And the interpretation is 
only indirectly evidence for whatever the patient may suffer from, and 
only if we trust or otherwise know the qualifications of the 
radiologist.  If we doubt, the interpretation is no evidence;  and if we 
know the interpretation is wrong, it is evidence that the radiologist 
made a mistake (and perhaps is not a good one), but certainly not 
evidence that the patient suffers from this or that.

> Interpretation also transforms raw data into recoded variables that is 
> also used as evidence, for example in interpreting raw EKG tracings to 
> give the label of "ventricular tachycardia" or recording a sodium of 150 
> as "high sodium."

This is a similar case, though if we are based on firm rules (e.g., if X 
 > 10 then X is high), this recoding is hardly an interpretation, it is 
just a lossy translation from quantitative to qualitative form.

But both 'evidence' and 'interpretation' are terms used with many 
meanings, and perhaps instead of trying to answer the question 'what is 
evidence?' it is better to define the term:  'evidence', for our 
purposes, means ...

vQ

Received on Tuesday, 12 June 2007 19:28:05 UTC