6. evidence based management: what is the best available evidence?
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6. Evidence based management:What is the best available evidence?
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5-step approach
EBMgt is a 5-step approach
1. Formulate an answerable question (PICOC)
2. Search for the best available evidence
3. Critically appraise the quality of the found evidence
4. Integrate the evidence with managerial expertise and organizational concerns and apply
5. Monitor and evaluate the results
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Why are disciplines as such as psychoanalysis, astrology and
parapsychology widely regarded as pseudo-science?
Intermezzo
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“It is easy to obtain evidence in favor of virtually any theory,
but such ‘corroboration’ should count scientifically only if it
is the positive result of a genuinely ‘risky’ prediction, which
might conceivably have been false.
… A theory is scientific only if it is refutable
by a conceivable event. Every genuine test
of a scientific theory, then, is logically an
attempt to refute or to falsify it.”
Falsifiability
Carl Popper
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“Inspect every piece of pseudoscience and you will find a
security blanket, a thumb to suck, a skirt to hold.
What have we to offer in exchange? Uncertainty!
Insecurity!”
Falsifiability
Isaac Asimov
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Research designs
What is the BEST car?
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Which design for which question?
Research designs
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Explanation
Which design for which question?
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Best research design?
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Best available?
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The best available evidence =
Studies with the highest internal validity
Studies with the highest external validity
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1. Best available evidence: internal validity
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internal validity = indicates to what extent the results of the research may be biased and is thus a comment on the degree to which alternative explanations for the outcome found are possible (confounding).
Internal validity
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Three criteria:
1. the "cause" and the "effect" are related
2. the "cause" precedes the "effect" in time
3. there are no plausible alternative explanations for the
observed effect
When do we know there is causal relation?
Causality
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Considerations for research:
Causality
1. Are the "cause" and the "effect” related: effect size
2. Does the "cause" precedes the "effect" in time:
before and after measurement
3. Are there no plausible alternative explanations for the
observed effect: randomization, control group
INTERNAL VALIDITY
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internal validity = indicates to what extent the
results of the research may be biased and is thus a comment on the degree to which alternative explanations for the outcome found
are possible (confounding).
Internal validity
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Bias
Confounding
Reverse Causation
Methodological pitfalls
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Bias: distortion of the outcome due to systematic errors caused by the way the study is designed or conducted.
NB: If bias is not taken into account then any conclusions drawn may be wrong!
Bias
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1. Selection bias
2. Information (detection) bias
3. Performance bias
4. Exclusion (attrition) bias
5. Publication bias
…
…
30. …..
Forms of bias
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Error in the way participants in a study were selected. Because of this comparison groups differ in measured or unmeasured baseline characteristics.
Selection bias
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Distortion of the outcome due to misinterpretation of information or systematic errors in the the measurement of research variables which leads to misclassification.
Information bias can be prevented by the use of standardized measurement instruments, hard outcome measures, validated questionnaires and objective, independent and blinded assessors.
Types of information bias:
Reporting bias (recall bias)
Observer bias (interviewer bias, halo-effect)
Information bias
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Confounding is the idea that a 3rd variable can distort or confuse (or confound..) a relationship between two other variables. For instance, when factor X causes disease Y, that relationship could be confounded by factor C that is associated with both factor X and disease Y. C would be an alternative explanation for the relationship observed between X and Y.
Confounding
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What are the confounders?
1. Shoe size & quality of handwriting
2. Body length & body weight
3. Number of storks & birth rate
4. Smoking youngsters & better lung function
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Confounding
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Correlation does not equal causation!
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http://kill-or-cure.heroku.com/
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Reverse causation
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?Successful companies
Charismatic leaders
Reverse causation
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Cause and effect can be established only through the proper research design: no amount of statistical hand waving can turn correlations into conclusions about causation !!!
Internal validity
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Levels of internal validity
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Levels of internal validity
It is shown that …
It is likely that …
Experts are of the opinion that …
There are signs that …
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The levels of internal validity can only be used to determine which type of research is the best method to assess the validity of the cause-and-effect relationship that might exist between an intervention (or moderator) and its outcomes. In this respect, cross-sectional studies and case-studies have the ‘weakest’ design. This of course doesn’t mean that cross-sectional studies and case-studies have a weak design overall. After all, different types of research questions require different types of research designs. A case study for instance is clearly a strong design for assessing why or in which way an effect has occurred, but obviously not the most suitable design for assessing the strength of a possible cause-and-effect relationship.
Keep in mind!
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But … sometimes observational studies are as good as RCT’s
Internal validity
When the size of effect is very large (swamps the bias)
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These treatments have not been tested in RCTs: are they supported by poor evidence?
Internal validity
Heimlich manoeuvre Dehydration: drinking water
Cardiac arrest: AED
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2. Best available evidence: external validity
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Ecological validity: Is your organization so different from those in the study that its results may be difficult to apply?
Population validity: Is your population so different from those in the study that its results may be difficult to apply?
External validity: generalizability
Always ask yourself to what extent the evidence is generalizable to your situation:
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Generalizability
Same Population?
Same Intervention?
Same Comparison?
Same Outcome?
Same Context?
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Generalizability
Keep in mind:
What works in one narrowly defined setting
might not work in another,
but some psychological principles
are generalizable to all human beings.
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Internal vs external validity
All research designs are flawed – though each is flawed differently. For instance, research designs with a high internal validity, such as controlled studies, may be less suited to generalization, which restricts their practical usability. Sample surveys and field research, on the other hand, have lower internal validity, but can sometimes be more useful for management practice. So there is always a trade off between internal validity (precision in control and measurements of variables) and external validity (generalizability with respect to populations, setting and context).
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Best available evidence?
internal validity often high
internal validity often low
external validity often low
external validity often …?
external validity sometimes high
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