05.13 · Cours 13 — Association, biais et confusion

Course 13 — Association, bias and confounding

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Association, Bias and Confounding

1Association, Bias and Confounding

Review of Previous Course

2Case-Control Studies and Odds Ratio 3Logistic Regression and Matching

4Session Objectives

Association and Its Forms

5Scientific Hypotheses as Associations 6Research Questions: PICO and PEO 7Statistical Analyses: Description and Inference 8Measures of Association

Five Explanations for an Association

9Causality, Reverse, Confounding, Bias, Chance 10Elimination Sequence Diagram 11Qualities of a Good Study

12Requirements for Causal Claims 13Hill's Nine Criteria for Causality

Confounding Effect

14Introduction to Confounding 15Third Variable Distorts A-B Link 16Example: Coffee, Smoking and Mortality 17Three Conditions for a Confounder 18Coffee-Mortality Cohort Study Design 19Age-Adjusted HR Shows Higher Mortality 20Baseline Characteristics Differ by Coffee Use 21Multivariate-Adjusted HR Reverses to 0.90 22Coffee Example Interpretation 23Detecting Confounding: Stratify and Compare 24Types of Confounding Effects 25Stratification Visualized in 3 Strata

Neutralizing Confounders

26Randomization and Matching 27Stratification and Statistical Adjustment 28Example: Height, Weight and Sex 29Crude Height-Weight Scatterplot 30Height-Weight Stratified by Sex 31Sex Confirmed as Confounder 32Simple Linear Regression: Weight on Height 33Multiple Regression: Adjusting for Sex 34Slope Reduced by One Third After Adjustment 35Reverse Direction: Height Confounds Sex-Weight 36Both Crude and Adjusted Are Correct 37Causal Chain vs Confounding

Bias and Chance

38Lecture Roadmap: Bias and Chance 39Random vs Systematic Errors 40Random Errors: CI, Type I and Type II 41Systematic Error: Bias Definition 42Bias Taxonomy: Selection, Information, Attenuation, Publication 43Selection Bias Examples 44Screening Bias: Breast Cancer Example 45Screening: Selection Bias in Who Gets Screened 46Screening: Length-Time (Prevalence) Bias 47Information Bias: Recall and Investigation 48Screening: Lead-Time Bias 49Misclassification Bias: Attenuation Toward Null 50Publication Bias: Fishing and Editorial Bias 51xkcd: Multiple Testing Jelly Bean Comic 52How to Prevent Bias

53Summary: Association Types and Five Explanations 54Summary: Confounding and Four Countermeasures

Next Session Preview

55Systematic Review and Meta-Analysis

05.13Page 1Association, Bias and Confounding

Cours 13 — Association, biais et confusion page 1

05.13Page 2Association, Bias and ConfoundingReview of Previous CourseCase-Control Studies and Odds Ratio

Cours 13 — Association, biais et confusion page 2

05.13Page 3Association, Bias and ConfoundingReview of Previous CourseLogistic Regression and Matching

Cours 13 — Association, biais et confusion page 3

05.13Page 4Association, Bias and ConfoundingSession Objectives

Cours 13 — Association, biais et confusion page 4

05.13Page 5Association, Bias and ConfoundingAssociation and Its FormsScientific Hypotheses as Associations

Cours 13 — Association, biais et confusion page 5

05.13Page 6Association, Bias and ConfoundingAssociation and Its FormsResearch Questions: PICO and PEO

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05.13Page 7Association, Bias and ConfoundingAssociation and Its FormsStatistical Analyses: Description and Inference

Cours 13 — Association, biais et confusion page 7

05.13Page 8Association, Bias and ConfoundingAssociation and Its FormsMeasures of Association

Cours 13 — Association, biais et confusion page 8

05.13Page 9Association, Bias and ConfoundingFive Explanations for an AssociationCausality, Reverse, Confounding, Bias, Chance

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05.13Page 10Association, Bias and ConfoundingFive Explanations for an AssociationElimination Sequence Diagram

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05.13Page 11Association, Bias and ConfoundingFive Explanations for an AssociationQualities of a Good Study

Cours 13 — Association, biais et confusion page 11

05.13Page 12Association, Bias and ConfoundingCausalityRequirements for Causal Claims

Cours 13 — Association, biais et confusion page 12

05.13Page 13Association, Bias and ConfoundingCausalityHill's Nine Criteria for Causality

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05.13Page 14Association, Bias and ConfoundingConfounding EffectIntroduction to Confounding

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05.13Page 15Association, Bias and ConfoundingConfounding EffectThird Variable Distorts A-B Link

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05.13Page 16Association, Bias and ConfoundingConfounding EffectExample: Coffee, Smoking and Mortality

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05.13Page 17Association, Bias and ConfoundingConfounding EffectThree Conditions for a Confounder

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05.13Page 18Association, Bias and ConfoundingConfounding EffectCoffee-Mortality Cohort Study Design

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05.13Page 19Association, Bias and ConfoundingConfounding EffectAge-Adjusted HR Shows Higher Mortality

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05.13Page 20Association, Bias and ConfoundingConfounding EffectBaseline Characteristics Differ by Coffee Use

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05.13Page 21Association, Bias and ConfoundingConfounding EffectMultivariate-Adjusted HR Reverses to 0.90

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05.13Page 22Association, Bias and ConfoundingConfounding EffectCoffee Example Interpretation

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05.13Page 23Association, Bias and ConfoundingConfounding EffectDetecting Confounding: Stratify and Compare

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05.13Page 24Association, Bias and ConfoundingConfounding EffectTypes of Confounding Effects

Cours 13 — Association, biais et confusion page 24

05.13Page 25Association, Bias and ConfoundingConfounding EffectStratification Visualized in 3 Strata

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05.13Page 26Association, Bias and ConfoundingNeutralizing ConfoundersRandomization and Matching

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05.13Page 27Association, Bias and ConfoundingNeutralizing ConfoundersStratification and Statistical Adjustment

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05.13Page 28Association, Bias and ConfoundingNeutralizing ConfoundersExample: Height, Weight and Sex

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05.13Page 29Association, Bias and ConfoundingNeutralizing ConfoundersCrude Height-Weight Scatterplot

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05.13Page 30Association, Bias and ConfoundingNeutralizing ConfoundersHeight-Weight Stratified by Sex

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05.13Page 31Association, Bias and ConfoundingNeutralizing ConfoundersSex Confirmed as Confounder

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05.13Page 32Association, Bias and ConfoundingNeutralizing ConfoundersSimple Linear Regression: Weight on Height

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05.13Page 33Association, Bias and ConfoundingNeutralizing ConfoundersMultiple Regression: Adjusting for Sex

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05.13Page 34Association, Bias and ConfoundingNeutralizing ConfoundersSlope Reduced by One Third After Adjustment

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05.13Page 35Association, Bias and ConfoundingNeutralizing ConfoundersReverse Direction: Height Confounds Sex-Weight

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05.13Page 36Association, Bias and ConfoundingNeutralizing ConfoundersBoth Crude and Adjusted Are Correct

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05.13Page 37Association, Bias and ConfoundingNeutralizing ConfoundersCausal Chain vs Confounding

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05.13Page 38Association, Bias and ConfoundingBias and ChanceLecture Roadmap: Bias and Chance

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05.13Page 39Association, Bias and ConfoundingBias and ChanceRandom vs Systematic Errors

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05.13Page 40Association, Bias and ConfoundingBias and ChanceRandom Errors: CI, Type I and Type II

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05.13Page 41Association, Bias and ConfoundingBias and ChanceSystematic Error: Bias Definition

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05.13Page 42Association, Bias and ConfoundingBias and ChanceBias Taxonomy: Selection, Information, Attenuation, Publication

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05.13Page 43Association, Bias and ConfoundingBias and ChanceSelection Bias Examples

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05.13Page 44Association, Bias and ConfoundingBias and ChanceScreening Bias: Breast Cancer Example

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05.13Page 45Association, Bias and ConfoundingBias and ChanceScreening: Selection Bias in Who Gets Screened

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05.13Page 46Association, Bias and ConfoundingBias and ChanceScreening: Length-Time (Prevalence) Bias

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05.13Page 47Association, Bias and ConfoundingBias and ChanceInformation Bias: Recall and Investigation

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05.13Page 48Association, Bias and ConfoundingBias and ChanceScreening: Lead-Time Bias

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05.13Page 49Association, Bias and ConfoundingBias and ChanceMisclassification Bias: Attenuation Toward Null

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05.13Page 50Association, Bias and ConfoundingBias and ChancePublication Bias: Fishing and Editorial Bias

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05.13Page 51Association, Bias and ConfoundingBias and Chancexkcd: Multiple Testing Jelly Bean Comic

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05.13Page 52Association, Bias and ConfoundingBias and ChanceHow to Prevent Bias

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05.13Page 53Association, Bias and ConfoundingConclusionsSummary: Association Types and Five Explanations

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05.13Page 54Association, Bias and ConfoundingConclusionsSummary: Confounding and Four Countermeasures

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05.13Page 55Association, Bias and ConfoundingNext Session PreviewSystematic Review and Meta-Analysis

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