What does it mean to make a decision in a dogmatic way?
Dogmatism: This is the best way to do it
- Without evidence
- Just do what you have been told
- plow ahead
What does it mean to make a decision in a political way?
- Policy: This is the way we do it around here
- Written and we follow these rules, don’t have to think about it
- Standardized; SOPs
- As a vet, you will follow these
What does it mean to make a decision based on experience?
- Experience: This way worked the last few times
- This worked the last few times, but you have seen results so you go by this
What does it mean to make a decision on a whim?
- Whim: This way might work
What does it mean to make a decision based on Nihilism?
- Nihilism: It doesn’t really matter what we do
What does it mean to make the “least worst” decision?
- ‘Least worst’: Do what you will regret the least
- Do what you think will cause the least amount of damage
What does it mean when you defer to experts to make a decision?
- Defer to experts: How would you do it?
What does it mean when you defer to the client to make a decision?
- Defer to client: How would you like to proceed?
- We now x,y,z what do you, as the client, want to do?
How do decision trees help with deciding what treatment option to use?
- Related to treatment options…
- Most of the time it’s self-evident based on cost, current knowledge, what you have been taught in school.
- “Doing what any other vet would have done”…; if you do what any other vet would have done, you will not be in trouble if something goes wrong. If something goes wrong –> governing body –> judge you and your decision –> if you can defend yourself, then they will back you up on it. What if what every other vet is doing is not the best option? What if there is a treatment that is better but is not well known?
- But sometimes… being methodical helps with our confidence and client communication
In what situations would you use a decision tree?
What are the disadvantages of a decision analysis?
–> Good situations to use decision analysis
* When you have competing treatment options with different risks and benefits
- E.g. Drug A (cheaper and does not work as well vs Drug B more expensive but works better; what are the pros and cons/risks - must be weighed).
* Important information is missing; We do not know what the conseq. are.
* …these tools of putting your thoughts on paper may identify critical information needs. (E.g. we could do this drug but we do not know much about the effects, must inform clients so that they make an informed decision.
* Risk occurs at different time points and the impact needs to be communicated to the owner
–> Disadvantages to decision analysis
* Time consuming and laborious; Go into literature, find out options –> consequences. To complete tree. If absence of evidence in tree = it can not be done. You can guestimate and fill in info but you are inventing branches which is bad.
* Cannot be performed in the absence of evidence
* Going through the exercise of building one will identify gaps of knowledge
Decision analysis is defined as “explicit and quantitative analysis of the ____ and _______ associated to available decisions under conditions of uncertainty.”
Cockroft, 2007
Comparing pros and cons for each decision
Decision analysis is defined as “explicit and quantitative analysis of the cost and benefit associated to available decisions under conditions of uncertainty.”
Cockroft, 2007
Comparing pros and cons for each decision
What is the methodology of Decision analysis?
What is the methodology of Decision analysis?
* Build a decision tree (a flow diagram with all possible scenarios)
* Add the probabilities of occurrence for each random event.
* Add the cost and/or the value (depends on if looking at pure cost but can also be a value trad production animals since apart of business (economical) but can also be on these values: moral, emotional) of each outcome.
* Compare the expected cost/value of each decision.
What the the three types of nodes?
Decision node, probability node, terminal node
Once you choose a decision node, can you go back?
No!
After you make a decision, all the _________ come after. These are chance nodes.
probabilities
Terminal node = ?
Value/cost at the end
- Decision node – represents a _______ decision between ___ or ____ options (e.g. choice of intervention).
- They are commonly represented as a ‘_______’
- Decision node – represents a conscious decision between 2 or more options (e.g. choice of intervention).
- They are commonly represented as a ‘square
conscious decision between several options. The probability is all the outcomes that happen after that decision has been made. At the very end of each branch, all the probabilities have to equal to 100%.
- Probability (_______) node – represents the outcome between ___ or _____ _______ events due to _______ (i.e. no ________ involved). Each outcome is associated with a probability (or likelihood), and the sum of the probabilities should be equal to ___ (i.e. _____%).
- They are commonly represented as a ‘_____’
- Probability (chance) node – represents the outcome between 2 or more random events due to chance (i.e. no decision involved). Each outcome is associated with a probability (or likelihood), and the sum of the probabilities should be equal to 1.0 (i.e. 100%).
- They are commonly represented as a ‘circle’
the probability is all of the outcomes that come after that decision is made. At the end of each branch, all the probabilities have to = 100%.
- Terminal node – represents the _____ of a scenario (tree branch) and is associated with an expected _____/_____ that combines both the _________ and the ______/_____ of the scenario.
- They are commonly represented as a ‘_____’
- Terminal node – represents the end of a scenario (tree branch) and is associated with an expected cost/value that combines both the probability and the cost/value of the scenario.
- They are commonly represented as a ‘triangle’
Example: Cost of treatment
You have 3 treatment options.
Option A = 40 lbs with an 80% chance of recovery.
- Most expensive with highest chance of recovery. Option B = 30, 60% chance recovery
Option C = 20, 40% chance recovery
Failure of any of these treatments –> 100 lbs follow up treatment
From a cost perspective, what will cost you less in the long run?
- What is the % failure for each option?
- If 100% successful, how much will each cost?
- If a treatment failed, how much will each cost?
- What is the cost of the outcome if the treatment is successful? If it fails?
- What is the cost of treatment per case?
Option A = 20% failure
Option B = 40% failure
Option C = 60% failure
Typically look at value of animal in terms of cost in food production animals.
Toggle makes the most sense because has the greatest value.
It is a cheaper option to do right away and there is still a very high chance of success with a lower chance of failure.
From a cost perspective, tell farmer to do toggling. However, farmer needs to know there is a 12% chance of the cow dying. So if life is more valuable for producer, toggling has a higher risk so they should choose Omentoplexy.
The last thing you should do is a sensitivity analysis which is you trying different values, changing probabilities and costs to see if it changes decision making process.
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Topic 1 - Introduction29
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Sampling Epidemiology57
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Infectious Diseases57
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Measures of Disease Frequency23
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Diagnostic Evaluation71
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Measures of Association43
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Disease Outbreak42
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Surveillance/Monitoring Systems66
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Topic 9 - Study Designs76
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Topic 1064
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EVidence Based Veterinary Medicine30
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Decision Analysis26
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Future of EBVM17
