25. ASSOCIATION VS CAUSATION

Question 1

1. What were Aristotle’s first thoughts on Causality?

Answer 1

• all causes of things are beginnings
• we obtain scientific knowledge when we establish the
  cause
• to understand something’s existence is to understand
  the reason why it exists

Question 2

2. How could we Paraphrase Aristotle’s thoughts on Causality?

Answer 2

• scientific knowledge requires explanations
• thee state the causes of outcomes

IT IS ESSENTIAL TO IDENTIFY A CAUSE:
- that causes an effect on health

Question 3

3. What is a Valid Association?

Answer 3

• a valid association is an exposure-outcome association
  that upholds 3 important criteria

Question 4

4. What are the criteria that a Valid Association upholds?

Answer 4

1. Chance
2. Bias
3. Confounding

Question 5

5. What is meant by “Chance”?

Answer 5

• chance has to be excluded as a possible explanation
  for the association

Question 6

6. What provides information on “Chance”?

Answer 6

• the p-value
• the 95% Confidence Interval

Question 7

7. What is meant by “Bias”?

Answer 7

• bias has to be excluded as a possible explanation for
  the association

Question 8

8. What provides information on “Bias”?

Answer 8

• there has to be a thorough check for errors
• this happens during Sample Selection and during the
  Assessment of Variables

Question 9

9. What is meant by “Confounding”?

Answer 9

• this has to be excluded as a possible explanation for
  the association

Question 10

10. What provides information on “Confounding”?

Answer 10

• the identification and adjustment of all the potential
  confounders

Question 11

11. Can every Valid association automatically be proven as a Causation?

Answer 11

• no
• association does not equal causation

Question 12

12. What is a Causal Association?

Answer 12

• this is one in which the exposure directly or indirectly
  causes the outcome of interest
• the exposure can also contribute to the development

Question 13

13. What exists in order to help us decide whether there is a Causal Association present?

Answer 13

• the Bradford Hill criteria for Causation

Question 14

14. What are the 9 parameters of the Bradford Hill Criteria?

Answer 14

1. Temporality
2. Strength
3. Biological Gradient
4. Reversibility
5. Consistency
6. Plausibility
7. Analogy
8. Coherence
9. Specificity

NB:
- the first 6 are the major and important criteria

Question 15

15. What is meant by “Temporality”?

Answer 15

• the exposure must precede the outcome
• the exposure must chronologically come before the
  outcome

IN OTHER WORDS:
- the suspected cause of the disease must happen
before the actual disease occurs

Question 16

16. What is this an example of?

Answer 16

• a Temporal Association
• it makes reference to “early life”
• the exposure is chronologically preceding the outcome

Question 17

17. What is this an example of?

Answer 17

• a Non-Temporal association
• it makes reference to current situations
• the exposure and the outcome are happening
  simultaneously

Question 18

18. What is meant by “Strength”?

Answer 18

THE STRONGER THE ASSOCIATION BETWEEN THE EXPOSURE AND THE OUTCOME:
- the more likely it is to be a form of Causation
- they are more likely to be causal

Question 19

19. What is this an example of?

Answer 19

• a Strong Association

THE RISK RATIO IS HIGH:
- since those who smoke are 4 times as likely to
experience lung cancer than those who do not

THE CONFIDENCE INTERVAL:
- is also very high

Question 20

20. What is this an example of?

Answer 20

• a weak Association

THE RISK RATIO IS A RELATIVELY LOW:
- since those who smoke are 10% more likely to
experience lung cancer than those who do not

THE CONFIDENCE INTERVAL:
- is also low

Question 21

21. What is meant by “Biological Gradient”?

Answer 21

• this is the dose-response association
• it exists between the exposure and the outcome

Question 22

22. What is this an example of?

Answer 22

• this is a Dose-Response association
• the dose and the response increase proportionally

Question 23

23. What is this an example of?

Answer 23

• this is not a Dose-Response association
• the dose and the response do not increase
  proportionally

Question 24

24. What is meant by: “Removing”?

Answer 24

• this is also known as Reducing
• removing or reducing the exposure will reduce the
  incidence of the outcome
• it can also reduce the severity

Question 25

25. What is this an example of?

Answer 25

• this is an Example where there is Reversibility in the
  association
• the exposure is reduced
• this reduces the outcome

Question 26

26. What is this an example of?

Answer 26

• this is an Example where there Reversibility does not
  exist in the association
• the exposure is reduced
• it does not have an effect on the outcome

Question 27

27. What is meant by: “Consistency”?

Answer 27

• the association between the exposure and the risk is
  observed in multiple situations and occasions

THE RESULTS CAN BE REPLICATED:
- in different populations
- with the use of different study designs

Question 28

28. What is this an example of?

Answer 28

• this is a Consistent Association

Question 29

29. What is this an example of?

Answer 29

• this is not a Consistent Association

Question 30

30. What is meant by “Plausability”?

Answer 30

• there exists a theoretically proven and logical
  explanation for the association between the exposure
  and the outcome

PLAUSIBILITY EXISTS:
- if we can find a biological mechanism or connection
that explains the association

Question 31

31. What is this an example of?

Answer 31

• this is a biologically PLAUSIBLE association

Question 32

32. What is this an example of?

Answer 32

• as association that is not biologically PLAUSIBLE
• there is no proof of current evidence