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Basic Statistics: The Three Things You Need to Know In Order to Complete Your Project
Edward P. Sloan, MD, MPH Associate Professor Dept of Emergency Medicine University of Illinois College of Medicine Chicago, IL
Attending Physician Emergency Medicine University of Illinois Hospital Our Lady of the Resurrection Medical Center
Overview Global Objectives Answer clinical questions Learn minimal statistics Get it done
Overview Session Objectives Know what question to ask Review stats needed to answer question Collect data for stat analysis
Three Things to Know What measurement? What question? How to report your results
Other Things to Know What data is needed? Basic statistical tests Nothing else
Two Measurements Proportion Mean
Two Questions What is the number? Do two groups differ?
Proportion Measurement What % of patients had some outcome? Divides a group into subgroups
Mean Measurement Describes a characteristic of a patient group Provides an overview
What is the Number? Describes one group Tells a story No comparisons
What #? Confidence Interval Can we believe the results? Was the process acceptable? Are the results reproducible?
Confidence Interval 95% CI Provides a range The “real” number is in this range
Do Two Groups Differ? Compares two groups Attempts to detect differences Relates outcomes to different interventions
Groups Differ? Hypothesis Test Null hypothesis, H o Alternate hypothesis, H A Are the groups the same (H o ) or different (H A )?
Hypothesis Test We reject H o The groups aren’t the same We then accept that they differ
Using Statistics 1)Pick your number type (Proportion or mean) 2)Decide what you will do (Describe or compare) (CI or hypothesis test) 3)Do the stat analysis 4)Report the results
Reporting Proportions 95% Confidence Interval In patients with T-wave inversion on their ED EKG, 29 (+ 3)% will develop an AMI during hospitalization (95% CI 26-32%).
Reporting Proportions: Hypothesis Test There was a two-fold greater 5 year survival rate in drug A patients vs. drug B patients (30% vs. 15%, p<.001)
Reporting Means: 95% Confidence Interval The mean CPK-MB in ED T-wave inversion AMI patients was 12 + 6 (95% CI=9-15).
Reporting Means: Hypothesis Test Drug A patients had a 50% greater survival time than that of drug B patients (1.5 + 0.7 years vs. 1.0 + 0.5 years, p<.001).
Statistics: Proportions Chi-square Fisher’s Exact test
Statistics: Means Students’s t-test ANOVA
Key Concepts: Design Know your number Know what question you’ll do Know how you will report results
Key Concepts: Data Collection Data to describe groups Data to compare groups Data to provide results Data to study confounding
Key Concepts: Data Analysis Simple data elements Ability to do 2x2 analysis Ability to do simple regression
Key Concepts: Reporting Consistent statements Straightforward p-value is less important
Statistics: Reporting Results Differences in outcome Absolute vs. Relative Mortality 25% to 20% –5% absolute decrease –20% relative decrease
Statistics: Reporting Results Odds ratios Relative risk Regression analysis What variables predict outcome?
Example: 2x2 Analysis Risk variable Outcome measure OR, 95% CI p-value Conclusion
Conclusions Know baseline proportions/means Project your results Know what data is needed Collect the data Analyze via 2x2 tables
Recommendations Keep it simple Follow our directions completely
Edward P. Sloan, MD, MPH, FACEP Research Lecture : Basic Statistics.
Research Design: The Progression of Study Designs that Address a Clinical Question.
Edward P. Sloan, MD, MPH Grant Opportunities in Emergency Medical Services & Bioterrorism Preparedness.
Edward P. Sloan, MD, MPH United States Health & Human Services: Programs & Resources for Emergency Medical Services.
Edward P. Sloan, MD, MPH, FACEP Basic Statistics for EM Research: Power Calculations.
Research Project Idea Generation: So Much to Do, So Little Time.
Edward P. Sloan, MD, MPH ICEP On Our Watch II: Lessons Learned September 14, 2004.
Edward P. Sloan, MD, MPH, FACEP Research Lecture Private Grant Writing.
Edward P. Sloan, MD, MPH, FACEP Manuscript Writing: How to Get your Manuscript Written Effectively and Easily.
Edward P. Sloan, MD, MPH, FACEP Conducting Successful EM Resident Research: Working with Databases.
ICEP Academic Forum April 29, 2004 Northwestern Memorial Hospital.
Edward P. Sloan, MD, MPH, FACEP Conducting Successful Emergency Medicine Research: Compelling Grant Writing.
Edward P. Sloan, MD, MPH, FACEP Conducting Successful EM Resident Research: Generating Research Ideas and Hypotheses.
Edward P. Sloan, MD, MPH ACEP Clinical Policy Clinical Policy: Critical Issues in the Management of Adult Patients Presenting to the Emergency Department.
Acute Ischemic Stroke Management: 2004 Emergency Medicine Perspectives.
Edward P. Sloan, MD, MPH, FACEP Conducting Successful EM Resident Research: 18 Month Research Plan.
Edward P. Sloan, MD, MPH, FACEP Successful Grantsmanship Private Grant Writing.
Research Curriculum Session III – Estimating Sample Size and Power Jim Quinn MD MS Research Director, Division of Emergency Medicine Stanford University.
Edward P. Sloan, MD, MPH, FACEP Conducting Successful EM Resident Research: Research Project Idea Generation.
Edward P. Sloan, MD, MPH, FACEP Emergency Department Patient Hypertensive Emergencies: Published Guidelines, Articles, & Their Findings.
The Research Requirement: An Overview of the 18 Step Process.
Edward P. Sloan, MD, MPH, FACEP Ischemic Stroke Patient Care: tPA Use in 2007.
The Use of Clinical Guidelines for Education Efforts in the Academic Setting.
Adult Seizure and SE Patient ED Care: Crossfire Edward P. Sloan, MD, MPH, FACEP 1.
Status Epilepticus (SE): Rx Following Benzodiazepine Use Edward Sloan, MD, MPH Associate Professor Department of Emergency Medicine University of Illinois.
Edward P. Sloan, MD, MPH EMRA/FERNE Neurological Emergencies Case Conference Special Panel Discussion: Tell me One Thing About Emergency Medicine.
Understanding p-values Annie Herbert Medical Statistician Research and Development Support Unit
Edward P. Sloan, MD, MPH, FACEP Conducting Successful EM Resident Research: Working with EM Faculty.
Optimal Pain Management for ED Patients: Issues in 2004 Edward P. Sloan, MD, MPH, FACEP Professor Department of Emergency Medicine University of Illinois.
November 5, 2014 Matthew Tuck, MD Hospitalist, Veterans Affairs Medical Center Assistant Professor of Medicine, George Washington University.
통계적 추론 (Statistical Inference) 삼성생명과학연구소 통계지원팀 김선우 1.
Critical Appraisal Course for Emergency Medicine Trainees Module 2 Statistics.
Edward P. Sloan, MD, MPH, FACEP Optimizing Seizure and SE Patient Management: Seizure Therapies Workshop and Clinical Policy Review.
Research Design & Methodology Edward P. Sloan, MD, MPH, FACEP Program in Emergency Medicine University of Illinois College of Medicine.
How confident are we in the estimation of mean/proportion we have calculated?
Various Topics of Interest to the Inquiring Orthopedist Richard Gerkin, MD, MS BGSMC GME Research.
FRAMING RESEARCH QUESTIONS The PICO Strategy. PICO P: Population of interest I: Intervention C: Control O: Outcome.
Smallpox Vaccination: Risk Assessment and Perspectives of the Health Care Provider, Institution, and State of Illinois.
The Argument for Using Statistics Weighing the Evidence Statistical Inference: An Overview Applying Statistical Inference: An Example Going Beyond Testing.
Probability & Statistical Inference Lecture 7 MSc in Computing (Data Analytics)
Clinical Trials in PKU Georgianne Arnold, MD Professor of Pediatrics
Statistical Fridays J C Horrow, MD, MS STAT Clinical Professor, Anesthesiology Drexel University College of Medicine.
Edward P. Sloan, MD, MPH, FACEP EMRA /FERNE Case Conference: The ED Management of Acute Ischemic Stroke Patients.
Edward P. Sloan, MD, MPH EMRA/FERNE ED Documentation Session: Optimizing the Care of ED Patients with Neurological Emergencies.
Edward P. Sloan, MD, MPH, FACEP Successful Grantmanship Government Grant Writing & the PHS 398 Form.
Edward P. Sloan, MD, MPH, FACEP Research Lecture The Successful Research Program: Ideas, The Research, and Presenting the Work.
Copyright © 2011 Pearson Education, Inc. Putting Statistics to Work.
January Structure of the book Section 1 (Ch 1 – 10) Basic concepts and techniques Section 2 (Ch 11 – 15): Inference for quantitative outcomes Section.
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