Sean Collins

Linda Crane Lecture 2018

Synthesis: Causal Models, Causal Knowledge

Text to Traci….

“I’ve decided to write the Linda Crane lecture as a speech - so I can practice it ahead of time and know that I say all that I want to say... It's certainly a different approach for me and I am not altogether comfortable with it yet; but this is certainly a different kind of lecture for me and I know that I am not altogether comfortable with it yet.”

Thank you!

• APTA• Parents• Educators and Mentors• Colleagues and Students• Family

Thank you!

• Dr. Linda Crane

Dr. Linda CraneHumble - Decisive - Passionate

“Humility is not synonymous with passivity or indecisiveness. One can hold beliefs passionately yet with humility. An awareness of the slipperiness of truth, the subtlety of error, and the human appetite for illusion does not mean one cannot believe and act with intensity. Acting with less than perfect knowledge is part of the risk of being human. But we should therefore reject self congratulating narrowness, always seeking a deepening and broadening of our understanding rather than a hardening of it.”

Daniel Taylor, The Myth of Certainty: The Reflective Christian and the Risk of Commitment

Acting with less than perfect knowledge is part of the risk of being human.

Knowledge based practiceSynthesis: Causal Models, Causal Knowledge

Acting with less than perfect knowledge is part of the risk of being human.

The Clinician’s Dilemma

Basic epistemological axioms

• Common Sense RealismLaw of Non contradictionLaw of CausationBasic reliability in sense perception’Analogical use of language

Knowledge and CompetenceCompetence requires knowledgeTherefore practice competence requires practice knowledge

Equivalent to:

Knowledge and Competence

Knowledge Based Practice

Uncontroversial:

Practice knowledge is a necessary but not a sufficient condition for practice competence

A knowledge based practice can help set the stage for practice competence

Knowledge Based Practice

• Synthesis• Building causal models• Generating inference rules based on the models

to inform practice based on that knowledge• Testing the established causal models

• Doing this all explicitly; not simply implicitly

The Clinician’s Dilemma

Acting with less than perfect knowledge is part of the risk of being human.

Evidence Based Practice Won’t Work

• It will not resolve the clinician’s dilemma• It will not create perfect knowledge

Evidence Based Practice Won’t Work

• It will not resolve the clinician’s dilemma• It will not create perfect knowledge

Context –

Yes, I am caricaturizing EBP, yes I realize no one is making the above claims

Early experience

• September 1992, MS in PT student• Told we had to pursue the MS degree to help

improve the profession’s ability to generate and use evidence for practice

• But also told that an answer to my question could not be answered and that I would eventually know the answer as I gained practice experience

Ergonomics & Epidemiology

Logic & Epistemology• Formal logic and inference

DeductionInductionAbduction

• Common Sense RealismNon contradictionAnalogical use of languageBasic reliability of sensory perceptionCausation

• Syntopical reading – synthesis

PTJ, 2003, Invited Commentary

“What can be done to stimulate more research in physical therapy that has direct clinical relevance?”Alan Jette

2005 - letter to editor, PTJ:“The simple study of parts in isolation -reductionism - is the modus operandi of the scientific method, attempting to isolate sources of variation. Clinicians, however, are faced with all sources of variation at the same time and must deal constantly with the full burden of the complex system.”

Collins, 2005

Critical Realism

Philosophical foundation for knowledge based practice

Explicitly identifies the human mind as part of the process of knowledge

Ontology (being: the way things are) determines epistemology (knowing: the way things are known)

The way practice is, should determine the way we know about practice

Critical Realism Definition (McGrath)

“Reality is apprehended by the human mind, which attempts to express and accommodate that reality as best it can with the tools at its disposal -such as mathematical formula or mental models.”

Alistair McGrath, Scientific Theology, Volume 2: Reality

Critical Realism

Critical realism explicitly identifies the human mind as part of the process of knowledge. This makes explicit use of models to represent the reality encountered. In other words - the mental models that are constructed are knowledge and their goal is to fit with reality even when we cannot empirically verify each and every component of such models.

Critical Realism

Ontology (being: the way things are) determines epistemology (knowing: the way things are known)

The way things are – there is a differentiation and stratification of reality

Critical Realism

McGrath: “The nature of reality is such that certain things can only be known to a certain extent, and in a certain way – and that this is the reality of the situation. We are not in a position to determine whether and how things may be known: that is decided by the things themselves.”

The way practice is, should determine the way we know about practice

Not a DAG

Special Thanks to the artist, Kirsten Enright, PSU DPT Class of 2020!

Special Thanks to the artist, Kirsten Enright, PSU DPT Class of 2020!

Special Thanks to the artist, Kirsten Enright, PSU DPT Class of 2020!

Special Thanks to the artist, Kirsten Enright, PSU DPT Class of 2020!

P(+Muscle_Function | +ES) > P(+Muscle_Function | −ES)

What about transitivity?• Evidence leads to knowledge• Knowledge informs practice• Therefore, evidence informs practice

Critical realist response: evidence does now translates to knowledge directly; evidence contributes to the transformation of knowledge as something that is ontologically distinct from what evidence can translate to.

2005 - letter to editor, PTJ:“The simple study of parts in isolation -reductionism - is the modus operandi of the scientific method, attempting to isolate sources of variation. Clinicians, however, are faced with all sources of variation at the same time and must deal constantly with the full burden of the complex system.”

Collins, 2005

Complexity – as a number of alternatives

AT ES0 00 11 01 1

22 = 4 23 = 8 24 = 16AT ES RT0 0 00 0 10 1 00 1 11 0 01 0 11 1 01 1 1

AT ES RT IMT0 0 0 00 0 0 10 0 1 00 0 1 10 1 0 00 1 0 10 1 1 00 1 1 11 0 0 01 0 0 11 0 1 01 0 1 11 1 0 01 1 0 11 1 1 01 1 1 1

25 = 3226 = 6427 = 12837 = 218747 = 16,384

SYNTHESIS: CAUSAL MODELS, CAUSAL KNOWLEDGE

THREE CLAIMSTWO PREMISESTHREE EXAMPLESONE SUMMARYONE CONCLUSION

SYNTHESIS: CAUSAL MODELS, CAUSAL KNOWLEDGE

THREE CLAIMS

Claim 1

Causal inferences are the most pervasive in all clinical reasoning

P e | i( ) > P(e)P e1 | i1( ) > P(e1 | i0 )

Claim 2Clinicians reason from cause to most likely effect when prescribing interventions and from effects to most likely cause during their evaluation

P i | e( ) = P(e | i) ⋅P i( )P e( )

P e | i( ) > P(e)P e1 | i1( ) > P(e1 | i0 )

Claim 3Causal inferences are central, either explicitly or implicitly, in all research as we attempt to generate understanding about cause and effect relations from our structured observations

SYNTHESIS: CAUSAL MODELS, CAUSAL KNOWLEDGE

TWO PREMISES

Premise 1

Explicitly outlined causal models provide us with a framework to iteratively build and share knowledge for practice and connects practice to research as well as research to practice

Premise 2

Causal models provide frameworks upon which inference patterns can be taught, learned, practiced, and improved upon

SYNTHESIS: CAUSAL MODELS, CAUSAL KNOWLEDGE

EXAMPLES

Features (common to all examples)• Causal models are a representation of clinical

knowledge, and thus can be used to develop clinical reasoning

• Causal models represent both causal structure and degrees of belief for research and practice

• Tools such as DAGitty (open source) and SAMIAM (open source) for the development, analysis and use of physical therapy causal models in practice and research

Examples

1. Social determinants of health2. Differential diagnosis3. From Effect Sizes to Conditional probabilities

SDOH – social determinants of health

http://dagitty.net/dags.html?id=AUlXbR

Differential Diagnosis

Differential Diagnosis: the abductive challenge

Deduction:Premise 1: If X, then YPremise 2: XConclusion: Therefore Y

Abduction:Premise 1: If X, then YPremise 2: YConclusion: Therefore X

Differential Diagnosis: abductive adjustment sets

• The process of differential diagnosis is essentially the process of identifying an adjustment set and testing (in some way) the members of that set

• First select the appropriate causal model for the given situation, then reason through it (implicitly or explicitly); reasoning explicitly may help reduce the risk of flawed reasoning and traps

Differential Diagnosis: abductive adjustment sets

• The abduction adjustment set must include all possible causes of the effects under consideration.

• Next step – more detail into each cause

!The adjustment set for the cardiac cause is now: {Ischemia, Pericarditis, Valve Dysfunction, Heart Failure}

!

Non Parameterized: adjustment set

21 = 223 = 8

24 = 16

What came first?

The nail or the hammer

Or perhaps the problem of fixing wood together

Data collection and use is driven by tools

With these tools in mind –

Data collection and use can be considered

With these data products available –

We can enter dialogue that attempts to bridge the crevasse between research evidence and the complexity of practice

Effect Sizes to Conditional probabilities

Effect sizes are extremely useful

But a clinician might also value a conditional probability when an intervention (or set of interventions) is proposed

NMES for heart failure

Gomes Neto et al. Journal of cardiopulmonary rehabilitation and prevention, 100(August):1, 2016.

SYNTHESIS: CAUSAL MODELS, CAUSAL KNOWLEDGE

ONE SUGGESTION

Suggestion

Let’s use causal models to provide a synthesisof what we know to develop causal knowledge from which to further develop with empirical evidence, and from which knowledge we can practice

SYNTHESIS: CAUSAL MODELS, CAUSAL KNOWLEDGE

ONE CONCLUSION

Causal models represent a synthesis of knowledge for practice with a critical realist epistemology that explicitly identifies the human mind as part of the process of knowledge and where the models that are constructed fits with reality even when we cannot empirically verify each and every component of such models; but where knowledge assumptions that are encoded in the models are clear, combine knowledge with reasoning, and are subject to empirical verification when possible.

Conclusion

THANKS FOR LISTENING!

QUESTIONS?