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

5Burwalls 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!

CASI Cork 11th to 13th May 2015© Swiss Statistical Society