Different viewpoints on Evidence across the HCLS Spectrum
Question: Can we come up with a uniform way of representing and reasoning with evidence across various HCLS contexts?
Biological View of Evidence
- Simple Pragmatic approach: Create a generic OWL annotation property (Matthias Samwald)
- Observation of Existence of A. e.g., experiment, XML file with results of the experiment, paper interpreting results
- Provides rationale/reason to believe in existence of B
- Focus on physical, biological and clinical reality, e.g., preference to experiment over
XML file or opinion of scientist
Clinical Research View of Evidence
- Clinical Trials Inclusion or Exclusion Criteria: Can we view these criteria as evidence (Karen Skinner)
- E.g., definition of a smoker, Fagerstorm Definition for Nicotine Dependence
- Evidence based View of Medicine: Classification of evidences (Dirk Coalert)
- Depends on the Source of Statement. The scale/weight of the evidence depends on various factors
- Opinion has the lowest ranking
- Results substantiated by a Randomized Clinical Trial with senstivity, specificity and confidence interval has the highest ranking
Clinical View of Evidence
- Radiology: Evidence is a function of the following (Daniel Rubin):
- The facts or observations
- The analysis method
- The inference
- The observer
- Clinical Obsevations and Judgements: Similar to the above and seems to be an instantation (Vipul Kashyap):
- The clinical observations which sometimes are not recorded
- Clinical Judgement, e.g., the pain suffered by the patient is moderate to severe
- Scores, e.g., Sometimes judgements are scored on a scale
- Mappings between the observations and the assessments.
- The inference or a set of aggregation and classification rules
- The observer, e.g., Patient, Nurse, Physician, etc.
- The instability of facts: Facts are not necessarily stable or consistent (Matt Williams):
- Mutliple physicians can have conflicting evaluations of patients
- Evidence may or may not be linked to probabilities, e.g. Wigmore Charts, Braden Risk Assessment Scale.
- But: Is there an underlying equivalence between these approaches and Probability Theory? (Vipul)
Experimental Data View of Evidence
- Use of provenance information, regarding 'How', by 'What method' and by 'Which agent' was a piece of data generated, as evidence to derive conclusions about the identity of data. (Satya Sahoo)
- When a list of peptides is derived from a 'biochemical sample' using mass spectrometry (ms) the evidence that accompany these results are:
- The details of the original sample (organism, type of cells, cleavage enzyme used etc.)
- The ms instrument used, the settings of the instruments, the algorithms used in processing the ms data, the databases used by the search algorithms etc.
- Hence, these types of evidence, for example a tryptic enzyme (trypsin or chymotrypsin) was used as cleaving agent for proteolysis, decides that the given data is specifically a list of 'tryptic' peptide.
- Evidence may be considered as subset of Provenance (Satya Sahoo and Cory Henson)
- Specific provenance parts, those that have a direct role to play in identifying a piece of data (with some amount of trust), may be classified as 'evidence'
- In some scenarios, evidence may also be a proper subset of provenance
Current Models of Evidential Reasoning
- Wigmore Charts (Wigmore, Tillers, Anderson, Twining)
- Toulmin-style (informal) argumentation (Toulmin)
- Bayes Net based approaches (Schum, Dawid)
There are a few scenarios that were discussed on the mailing list. These were X-rays, physical examination findings, clinical trial results and classification of patients according to some criteria.
= A quick Toulmin-style Model of Evidence
- Some terms:
Toulmin described the different parts of an argument as the datum, the warrant, the backing, claim and qualifier; I will ignore the last one and attempt to apply the others to this domain. However, as we shall see I think we need to refine some of these.
- The datum is the information we have about this case/ instance/ individual
- The warrant is a statement about some general case that we may apply in this situation, to this datum
- The claim is the result of the application of the warrant
- The backing is the more technical basis on which the warrant is given
In the examples above, therefore:
- The X-ray:
The datum is the patient's X-ray; the warrant is the interpretation of this x-ray; the backing is the radiologist; the claim is the radiologist's report
- The Classification of a smoker:
The datum is the patient's questionnaire score; the warrant is the mapping of scores to categories of dependence; the backing is the published justification of such a mapping; the claim is the classification category that the patient is put in.
- Wiki Page on BFO:Process
- ProPreO ontology (http://knoesis.wright.edu/students/satya/ProPreO-060707.owl)
- Tillers (http://tillerstillers at blogs**t.com/)
- Int. Commentary on Evidence (http://www.bepress.com/ice/)