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Teaching EBM in homeopathic doses. Amanda Burls Oxford, September 2005. Amanda Burls . C ritical A ppraisal S kills P rogramme making sense of evidence. General origins: The need to be evidence-based. Wide variations in practice Continued use of ineffective treatments
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Teaching EBM in homeopathic doses Amanda Burls Oxford, September 2005 Amanda Burls
General origins:The need to be evidence-based • Wide variations in practice • Continued use of ineffective treatments • Excess use of inappropriate treatments • Poor uptake of effective practice • Increasing consumerism • Increasing demand on resources • Exponential growth in research evidence
Local origins: • 1980s – Getting Research into Practice Project (GRiPP) • 1990 – Evaluation of barriers Lack of understanding of need for evidence-based practice amongst managers and policy makers • 1992 – Critical appraisal workshops piloted • 1993 – Critical Appraisal Skills Programme • 1994 – Finding the Evidence Workshops
Typical CASP workshop format • 1/2 day workshops • Structure Introductory talk Small group work Plenary discussion • Problem-based, using real papers on, e.g. Randomised controlled trials Systematic reviews Evaluations of diagnostic tests Economic evaluations Qualitative studies
Philosophy • Problem based • Interactive/participative • Small group learning • Building on people’s own knowledge and experience • Fun and safe • Learning to recognise, admit and cope with uncertainty • Multidisciplinary • Where possible in peoples’ workplace • Cascading skills
Small group learning Using and building on people’s own experience, skills and knowlege
CASP learning experience Safe learning environment
Fun Problem
Teaching EBM in homeopathic doses Amanda Burls Oxford, September 2005
Models of education 1 • Filling the empty vessel
Models of education 2 Learning is a natural process Teaching is facilitation of growth
Models of education 2 • Learning is a natural process • Teaching is facilitation of growth
Models of education • Learning is a natural process • Teaching is facilitation of growth
What do you think health care practitioners need to know about ODDS RATIOS • Minimum that is useful • Optimal • Please feel free to discuss with your neighbours
Teaching p-values DIB: • Create the need for the concept of the p-value by getting participants to reject spontaneously a ridiculously small study
RCT: Well conducted no bias • 5 people with backache received Potters • 5 people received placebo • 4 out of 5 with Potters got better • 2 out of 5 with placebo got better
Participants are not convinced…“It could have happened by chance!” • So how many would you want before you believe the results? • 10 in each arm? • 20? • 100?
It could have happened by chance and nothing was really going on Uumm..... The “Null Hypothesis”
The p-value • What does a p-value of 5 tell us? • Use with great care…
1 0 So what does p=0.5 mean? So what does p=0.1 mean? So what does p=0.05 mean? Absolutely certain Impossible
Before I show the homeopathic dose of confidence intervals, let´s explore your views…
Clifton 1993 Clifton 1992 Hirayama 1994 Marion 1997 Total (95%CI) .1 .2 1 5 10 Hypothermia vs. control In severe head injury Mortality or incapacity (n=158) RR 0.63 (0.46, 0.87) RR
Clifton 1993 Clifton 1992 Hirayama 1994 Marion 1997 Total (95%CI) .1 .2 1 5 10 Hypothermia vs. control In severe head injury Mortality or incapacity (n=158) RR 0.63 (0.46, 0.87) Favours intervention RR Favours control
Confidence intervals are based on the assumption that a study provides one sample of observations out of many possible samples that would be derived if the study were repeated many times. For a 95% confidence interval, if the experiment were repeated many times, 95% of the intervals would contain the true treatment effect. The confidence interval (CI) is the range within which the true size of effect (never known exactly) lies, with a given degree of assurance. People often speak of a “95% confidence interval” (or “95% confidence limits”), this is the interval which includes the true value with 95% certainty. Confidence IntervalsWhich definition is better?
Clifton 1993 Clifton 1992 Hirayama 1994 Marion 1997 Total (95%CI) .1 .2 1 5 10 Hypothermia vs. control In severe head injury Mortality or incapacity (n=158) RR 0.63 (0.46, 0.87) Favours intervention RR Favours control
Moral: Any observed diffference between two groups, no matter how small, can be made to be “statistically significant” - at any level of significance - by taking a sufficiently large sample.
Teaching confidence intervals The Modified Franks Method (with Jose´s help)