Ambiguity and Ambiguity and Vagueness in Clinical Vagueness in Clinical Practice GuidelinesPractice Guidelines
Shlomi Codish, MDShlomi Codish, MDRichard Shiffman, MD, MCISRichard Shiffman, MD, MCIS
Yale Center for Medical Yale Center for Medical InformaticsInformatics
OverviewOverview
Definitions and backgroundDefinitions and background Classification modelClassification model Implications for authoring and Implications for authoring and
implementationimplementation
Linguistic definitionsLinguistic definitions
Vague: lacking clear borders, Vague: lacking clear borders, having borderline cases having borderline cases ““Dan is tall.”Dan is tall.”
Ambiguous: capable of being Ambiguous: capable of being understood in two or more understood in two or more possible senses or wayspossible senses or ways““I will meet you at the bank.”I will meet you at the bank.”
IntroductionIntroduction
Focus: human users of CPGsFocus: human users of CPGs Clinicians – reduced adherence or accuracyClinicians – reduced adherence or accuracy
Grol (1998), Shekelle (2000)Grol (1998), Shekelle (2000)
ImplementersImplementers
Ambiguity is often used to describe Ambiguity is often used to describe vaguenessvagueness ““disambiguation” has been used for the disambiguation” has been used for the
resolution of both ambiguity and vaguenessresolution of both ambiguity and vagueness
Research on vague Research on vague termsterms
Kong et al. NEJM 1986 Kong et al. NEJM 1986 ““qualitative expressions of probability”qualitative expressions of probability” Large variability in interpretationLarge variability in interpretation Comparable ranking as in previous Comparable ranking as in previous
study for 7 terms despite variable study for 7 terms despite variable interpretation :interpretation : certain > probable > likely > not certain > probable > likely > not
unreasonable >unreasonable >possible > unlikely > neverpossible > unlikely > never
Other factors affecting Other factors affecting interpretationinterpretation
Mapes (1979) – importance of contextMapes (1979) – importance of context Compare interpretation of Compare interpretation of rarerare in: in:
“…“…in the case of this beta blocker drug side effects are in the case of this beta blocker drug side effects are rarerare””
“…“…in the case of this antihistaminic drug side effects are in the case of this antihistaminic drug side effects are rarerare””
Kahneman and Tversky – importance of framingKahneman and Tversky – importance of framing Decision making affected by framingDecision making affected by framing
Options presented in terms of Options presented in terms of lives savedlives saved or or lives lostlives lost
ambiguity ≠ uncertaintyambiguity ≠ uncertainty
NJ judge to rule on nude beachNJ judge to rule on nude beach
Stolen painting found by treeStolen painting found by tree
Prostitutes appeal to governorProstitutes appeal to governor
OverviewOverview
IntroductionIntroduction Classification model for ambiguity Classification model for ambiguity
and vaguenessand vagueness Implications for authoring and Implications for authoring and
implementationimplementation
Development Development methodologymethodology
MEDLINE and Web of Science MEDLINE and Web of Science databasesdatabases
Review of the linguistics literatureReview of the linguistics literature Lists of terms and categoriesLists of terms and categories Validation with random collection of Validation with random collection of
100 CPG100 CPG
Model AxesModel Axes
Axis I: Ambiguity or vagueness?Axis I: Ambiguity or vagueness? Sub classification of ambiguitySub classification of ambiguity Sub classification of vaguenessSub classification of vagueness
Axis II: RationaleAxis II: Rationale Deliberate or inadvertentDeliberate or inadvertent Causes of deliberate vaguenessCauses of deliberate vagueness
Axis III: ImplementersAxis III: Implementers Logical component affectedLogical component affected If <condition> then <action> because If <condition> then <action> because
<explanation><explanation>
Axis 1 - AmbiguityAxis 1 - Ambiguity
Syntactic ambiguity: Syntactic ambiguity: structure or syntaxstructure or syntax ……mother with untreated disease mother with untreated disease oror disease that has disease that has
been treated for 2 or more weeks been treated for 2 or more weeks andand is who is judged is who is judged
to be noncontagious at the time of delivery…to be noncontagious at the time of delivery…
Semantic ambiguity: “classic” ambiguity Semantic ambiguity: “classic” ambiguity
Pragmatic ambiguity: reader and writer have Pragmatic ambiguity: reader and writer have
different interpretationsdifferent interpretations Example: Example: Disclosure of adolescent HIV status Disclosure of adolescent HIV status should should
legally requirelegally require the consent of the adolescent. the consent of the adolescent.
(()
)
Pragmatic ambiguityPragmatic ambiguity
3
cm
4 cm
x
3. Find x.
Here it is
Ocular Trauma – by Wade Clarke © 2005
Axis 1 - VaguenessAxis 1 - Vagueness Underspecification is a form of vagueness Underspecification is a form of vagueness
that occurs when terms are used with that occurs when terms are used with insufficient details for interpretation.insufficient details for interpretation. moderate, severe, elderly, adultmoderate, severe, elderly, adult ……should be treated should be treated promptlypromptly and and aggressivelyaggressively..
Ordinal scales of underspecified wordsOrdinal scales of underspecified words
Temporal scale:
Probabilistic scale:
Quantitative scale:
Never
Always
Impossible
None
Certain
All
rare sometimes
common
unlikely possible
probable
few some many
Axis I - VaguenessAxis I - Vagueness
Strength qualifiers (a.k.a. hedges)Strength qualifiers (a.k.a. hedges) It is It is generally recommendedgenerally recommended that the that the
antibiotic beads be removed 2 weeks…antibiotic beads be removed 2 weeks… It is prudent to…It is prudent to…
Passive voicePassive voice Memory complaints should be evaluated and Memory complaints should be evaluated and
the individual followed to assess progressionthe individual followed to assess progression
Axis II - rationaleAxis II - rationale
Only the authors know the rationale Only the authors know the rationale Inadvertent ambiguity or vagueness Inadvertent ambiguity or vagueness
is a failure of authoring and editingis a failure of authoring and editing It might also result from a failure to It might also result from a failure to
recognize the problems ambiguity recognize the problems ambiguity and vagueness create:and vagueness create: “…“…please appreciate that we will not please appreciate that we will not
necessarily have full agreement on the necessarily have full agreement on the fine points of wording as each of us has fine points of wording as each of us has his or her own writing style…” his or her own writing style…”
Axis II – deliberate Axis II – deliberate vaguenessvagueness
Insufficient scientific evidenceInsufficient scientific evidence Lack of consensus among authorsLack of consensus among authors Other considerationsOther considerations
LegalLegal EconomicEconomic EthicalEthical ReligiousReligious
Axis III – logical Axis III – logical componentcomponent
The logical part affected by The logical part affected by vagueness impacts vagueness impacts implementation:implementation: <condition> affects <condition> affects decidabilitydecidability <action> impacts <action> impacts executabilityexecutability <explanation> does not seriously <explanation> does not seriously
impact implementabilityimpact implementability
Axis I
VaguenessAmbiguity
Semantic
Pragmatic
Syntactic
Strength qualifiers
Underspecification
Passive voice
Probabilistic QuantitativeTemporal Non-ordinalunderspecification
Axis II
Deliberate Inadvertent
Ethical/Religious
Legal
Insufficient Scientific background
Economic
Axis III
Action (executability)
Explanation
Condition(decidability)
Ambiguity or vagueness in CPG recommendation
OverviewOverview
IntroductionIntroduction Classification modelClassification model Implications for authoring and Implications for authoring and
implementationimplementation
Remedies – axis 1Remedies – axis 1
Numerical values (or ranges) for Numerical values (or ranges) for termsterms
Ranking words relative to one Ranking words relative to one anotheranother
Lists of ‘good’ and ‘bad’ termsLists of ‘good’ and ‘bad’ terms Controlled vocabularyControlled vocabulary
BI-RADS “BI-RADS “Suspicious Abnormality—Suspicious Abnormality—Biopsy Should Be ConsideredBiopsy Should Be Considered””
Fuzzy logicFuzzy logic
Remedies – axis 2Remedies – axis 2 Reason should be documentedReason should be documented
……activated protein C should not be routinely used…activated protein C should not be routinely used… ……activated protein C should not be routinely used activated protein C should not be routinely used
because of its high cost…because of its high cost… Selecting a vague term should consider the Selecting a vague term should consider the
audienceaudience The range of interpretation by the intended audienceThe range of interpretation by the intended audience Other terms with similar meaningOther terms with similar meaning Avoid terms with wide range of interpretationAvoid terms with wide range of interpretation
Limit the scope of vaguenessLimit the scope of vagueness Cigarette smoking may be hazardous to your healthCigarette smoking may be hazardous to your health Smoking causes lung cancer, heart disease, emphysema Smoking causes lung cancer, heart disease, emphysema
and may complicate pregnancyand may complicate pregnancy Clarification of deliberate vagueness should be Clarification of deliberate vagueness should be
done with author inputdone with author input
SummarySummary
Vagueness is a common problem in CPG Vagueness is a common problem in CPG
recommendationsrecommendations ““Classic” (i.e. semantic) ambiguity is uncommonClassic” (i.e. semantic) ambiguity is uncommon
Distinct forms of vagueness and ambiguity Distinct forms of vagueness and ambiguity
require specific remediesrequire specific remedies When deliberate vagueness is deemed necessary, When deliberate vagueness is deemed necessary,
end-user uncertainty should be minimizedend-user uncertainty should be minimized Clarification of deliberate vagueness must Clarification of deliberate vagueness must
consider the rationale for the vaguenessconsider the rationale for the vagueness
Everything is vague to a degree Everything is vague to a degree you do not realize till you have you do not realize till you have
tried to make it precise.tried to make it precise.
Bertrand Russell, 1918Bertrand Russell, 1918
AcknowledgementsAcknowledgements
Prof. Laurence HornProf. Laurence HornYale LinguisticsYale Linguistics
National Library of National Library of MedicineMedicine