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Jeremy Howick Centre for Evidence-Based Medicine.

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Presentation on theme: "Jeremy Howick Centre for Evidence-Based Medicine."— Presentation transcript:

1 Jeremy Howick Centre for Evidence-Based Medicine

2 1. There are no hierarchies 2. EBM has always recognized mechanisms 3. Philosophers of science have ignored problems with the evidential role of mechanisms 4. The fact that ‘mechanistically sound’ hypotheses are more believable is irrelevant. 5. The best way to improve evidence would be to have a minimum effect size requirement

3 1. There are no hierarchies: GRADE Downgrade for: - Inconsistency - Indirectness - Imprecision - Publication bias Upgrade for: - Large consistent effect - Dose response - Confounders only reducing size of effect HIGH MODERATE LOW VERY LOW Step 1: Initial ranking Step 2: upgrade/downgrad e Step 3: assign final grade RT: High OS: low

4 1. There are no hierarchies: OCEBM randomized trial Cohort Study Case Series Mechanistic reasoning systematic review

5 2. EBM has always recognized a role for mechanisms

6 3. Proponents of mechanisms have ignore problems with mechanisms

7 4. Getting the contrast class right

8 4. Effect size

9 1. There are no hierarchies 2. EBM has always recognized mechanisms 3. Philosophers of science have ignored problems with the evidential role of mechanisms 4. The fact that ‘mechanistically sound’ hypotheses are more believable is irrelevant. 5. The best way to improve evidence would be to have a minimum effect size requirement

10 Thanks again! jeremy.howick@phc.ox.ac.uk


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