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Communicating StatisticsWhat is the message?
Philip SedgwickSt. George’s, University of London
Burwalls: King’s College London.UK Annual Meeting for Teachers of Medical Statistics, July 1st to 3rd 2015.
Burwalls 1st to 3rd July 2015
IntroductionTeaching statistics:
• Use of words?
• Impact on message?
• Expectations in application. From research setting to…. ….Patients and public.
• Current teaching examples.
Burwalls 1st to 3rd July 2015
My BackgroundTeaching medical statistics:
• Thirty years.
• MBBS, MRes. & MSc. students.
• MBBS: School Leavers and Graduate Entry.
Kaplan-Meier Survival Curves
• Aim: Evaluate effectiveness integrated care programme for patients with chronic low back pain.
• Design: Randomised controlled trial.
• Intervention (I): Combined patient-directed and workplace-directed intervention; one year follow-up.
• Control (C): Usual care.
• Participants: 134 adults (18-65), sick listed ≥ 12 wks due to low back pain.
• Outcome: Full sustained return to work.
• Survival times: Time until outcome.
4(BMJ 2010;340:c1035) Burwalls 1st to 3rd July 2015
• Median duration:
Intervention: 88 days; Control: 208 days.
• One year estimates (approximate):
Intervention: 75%; Control: 65%.
• Log Rank Test: P=0.003
• Hazard Ratio (HR) = 1.9; 95% Cl 1.2 to 2.8; P=0.004
Intervention: Significantly shorter times than control.
Key Points: Teaching
Burwalls 1st to 3rd July 2015
• Patient experience? Describe benefits treatment (median duration)? May not benefit from intervention? Enhanced recovery with control? May not return to work.
Nonetheless - Message is:
• Intervention: Significantly shorter times than control.
Application
Burwalls 1st to 3rd July 2015
• Statistics: Culture of significance and superiority.
• Group experience: P-values & 95% CI.
• Conflict between “evidence” and pragmatism.
• What is the message? Teacher to Student? Student (Doctor) to Patient?
Challenges
Burwalls 1st to 3rd July 2015
Words Confuse?• Statistical Significance
P < 0.05; 95% CI (Based on same theory).
• Significance: Everyday meaning = Importance.
• Statistics: Does not equate to importance. Group experience: Relevance to population.
Burwalls 1st to 3rd July 2015
The death of the P-value:What a chance!?
• Journal of Basic and Applied Social Psychology.
• Ban on hypothesis testing.
Burwalls 1st to 3rd July 2015
• Ban on significance versus ban on P-value.
What is Chance?
• Statistics: Synonymous with risk.
• Chance: Noun, adjective or verb.
• Culturally loaded society. “Words matter and confuse”. Teacher, student & patient.
• Banned.
• Odds, bias, error, confidence, qualitative expressions of risk,
Burwalls 1st to 3rd July 2015
A Choice of Words
CASI Cork 11th to 13th May 2015
Concluding Thoughts • Teaching
Curriculum: Modern needs; Teaching is about relevance, not just facts; People are not statistics.
• Culturally loaded society. “Words matter and confuse”. Use your words wisely!