Association Causation - PowerPoint PPT Presentation

Loading...

PPT – Association Causation PowerPoint presentation | free to download - id: 4edb3f-OWI5N



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Association Causation

Description:

Association Causation Marshall Tulloch-Reid Epidemiology Research Unit Tropical Medicine Research Institute Objectives Differentiate Association from Causation ... – PowerPoint PPT presentation

Number of Views:70
Avg rating:3.0/5.0
Slides: 20
Provided by: 10015
Learn more at: http://www.mona.uwi.edu
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Association Causation


1
Association Causation
  • Marshall Tulloch-Reid
  • Epidemiology Research Unit
  • Tropical Medicine Research Institute

2
Objectives
  1. Differentiate Association from Causation
  2. Understand the causal pie model for disease
    causation
  3. List and discuss some of the criteria that have
    been used for deciding between association and
    causation Henle Koch Postulates the
    Bradford Hill Criteria
  4. Understand the limitations of these criteria

3
Association Causation
  • Variables are associated if a statistical
    relationship exists between them
  • Statistical association does not imply a causal
    relationship between the variables

4
Association Causation
Population Hat Wearing Obesity
A 20 20
B 40 40
C 60 60
5
Association Causation
r 0.5
6
Association Causation Hats and Obesity
Percent Hats
Percent Obese
Group A B C
20 40 60
20 40 60
7
Concepts in Causation
  • The trigger of an event is often thought of as
    its cause
  • Most events are the result of the interaction of
    several causes
  • These causes do not need to occur simultaneously

8
Concepts in Causation
  • A 88 year old women with uncontrolled type 2
    diabetes and poor vision from diabetic
    retinopathy and glaucoma falls and fractures her
    hip.
  • What caused the hip fracture?

9
Concepts in CausationWhat caused the hip
fracture?
  • The fall
  • Poor vision
  • Hypoglycemia
  • Neuropathy
  • Non-compliance with treatment
  • Age
  • Osteoporosis
  • Genetic factors
  • No non-skid rug
  • Not wearing a hip protective device
  • The dog

10
The Causal Pie
Single Component Cause
Sufficient Cause
11
The Causal Pie
SF II
SF I
SF III
SF sufficient cause
12
The Causal Pie
  • Sufficient cause
  • Component Cause
  • Necessary Cause

13
Causality and the Scientific Method
  • Inductive method
  • Observations induce in the mind of the observer a
    suggestion for a more general statement
  • David Hume inductive method depends on circular
    reasoning

14
Causality and the Scientific Method
  • Refutation
  • Karl Popper statements about nature can be
    corroborated by evidence but it does not amount
    to logical proof however statements can be
    refuted by deductive logic

15
Criteria for Causation
  • A checklist is often employed to resolve issues
    of causation vs. association
  • Koch and Henle proposed criteria for infectious
    agents causing disease
  • The Bradford-Hill criteria is most often used for
    this purpose and can be more generally applied

16
Criteria for Causation
  • First questions to be answered
  • Are the findings due to chance?
  • Are the findings due to bias?
  • Are the findings due to confounding?

17
Criteria for Causation Henle-Koch Postulates
  • The organism is always found with the disease
  • The organism is not found in any other disease
  • The organism, isolated from one who has the
    disease, and cultured through several
    generations, produces the disease (in
    experimental animals)

18
Criteria for CausationBradford Hill Criteria
  • Temporal relationship
  • Strength of the association
  • Dose-response relationship
  • Replication of findings
  • Biologic plausibility
  • Alternative explanations
  • Cessation of exposure
  • Specificity of the association
  • Consistency with other knowledge

19
Criteria for Causation
  • Not all the criteria have to be meet for
    causality to be implied
  • Some criteria carry more weight than others
About PowerShow.com