This document discusses the differences between association and causation. Association is when two variables occur together more often than chance, while causation means one variable directly causes the other. There are three types of associations - spurious associations which are not real, indirect associations where a third factor links two variables, and direct associations where one variable directly causes the other in either a one-to-one or multifactorial relationship. The Bradford Hill criteria are discussed as a way to judge causality, considering factors like temporal relationship, strength of association, specificity, consistency, and biological plausibility.

1. ASSOCIATION AND CAUSATION
KESHAVA PAVAN K
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2. INTRODUCTION
 Association is the concurrence of two variables more
often than would be expected by chance.
 Events are said to be associated when they occur
more frequently together than one would expect by
chance
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3. TYPES
 Spurious
 Indirect
 Direct
 One-to-one
 multifactorial
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4. SPURIOUS ASSOCIATION
 Appears due to improper comparison
 Observed association between a disease & suspected
factor may not be real.
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5. INDIRECT ASSOCIATION
 Statistical association between a character of interest
and a disease due to presence of another factor,
known or unknown, that is common to both the
factors.
Altitude
 Iodine deficiency
Endemic goitre
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6. DIRECT ASSOCIATION
 Between two attributes that are directly related to
each other.
 One-to-one causation: when disease is present, factor
must also be present. e.g., Hemolytic streptococci
causing tonsillitis, scarlet fever, erysipelas
 Multifactorial causation: alternative causative factors
acting independently. e.g., lung cancer being caused
by smoking, air pollutants.
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7. CRITERIA FOR JUDGING CAUSALITY
Bradford Hill report, 1964
 Temporal association
 Strength of association
 Specificity of association
 Consistency of association
 Biological plausability
 Coherence of association
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8. TEMPORAL ASSOCIATION
 Causal attribute must precede the disease or
unfavourable outcome
 Exposure to factor must have occurred before the
disease developed
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9. STRENGTH OF ASSOCIATION
 If the association is strong or weak
 With increased level of exposure to risk factor,
incidence of disease increases.
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10. SPECIFICITY OF ASSOCIATION
 One to one relation between cause and effect
 Weakest of the criteria
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11. CONSISTENCY OF ASSOCIATION
 Occurrence of association at some other time & place
repeatedly.
 If a relationship is causal, findings should be
consistent with other data.
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12. BIOLOGICAL PLAUSABILITY
 Association must be consistent with other knowledge
like mechanism of action, evidence from animal
experiments etc.
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13. COHERENCE OF ASSOCIATION
 Causal significance of an association is its unity with
known facts that are thought to be related.
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14. THANK YOU
 THANK YOU for reading my presentation.
 If you have any doubts or interesting cases in any subject of
medicine, I will be delighted if you share at
keshavapavan533@gmail.com
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