Module 5

Question 1

List Hill’s postulates to determine causality.

Answer 1

1. strength of association
2. consistency/reproducibility
3. specificity
4. temporality
5. biological gradient
6. biological plausibility
7. coherence
8. experimental evidence
9. analogy

Question 2

What does strength of association refer to within Hill’s postulates?

Answer 2

Stronger measured effect of IV on DV or stronger relationship indicates greater likelihood of causal relationship

Question 3

Explain the postulate of consistency or reproducibility.

Answer 3

When findings supported in all studies within diff. populations, locations, and with diff. methods, then stronger likelihood of causal relationship

Question 4

Specificity within Hill’s postulates refers to…

Answer 4

The effect observed in DV being exclusively in response to changes in the IV.

Question 5

Which postulate is necessary for causality? Explain why.

Answer 5

Temporality, as this indicates that IV/exposure must be before effect in DV/outcome is observed

Question 6

What do biological gradient and biological plausibility refer to within Hill’s postulates?

Answer 6

Biological gradient: dose response is observed (for example: small exposure results in small effect, large exposure results in large effect)

Biological plausibility: a mechanism can explain relationship between IV and DV

Question 7

What does coherence mean in the context of determining causation?

Answer 7

Observation is consistent with what is already known

Question 8

What does postulate 9, analogy, mean?

Answer 8

Similar IVs have had similar effects on similar DVs

Question 9

What are the three types of associations?

Answer 9

Spurious, non-causal, causal

Question 10

In epidemiology, which two broad parameters are used to measure the distribution of outcomes in populations?

Answer 10

Prevalence and incidence

Question 11

How is relative risk interpreted if RR=1?

Answer 11

Risk/incidence proportion of outcome is equal in each group

Exposed group is equally likely to develop outcome as group that was not exposed

Question 12

How is relative risk interpreted if RR>1?

Answer 12

Risk/incidence proportion is higher in exposed group

Exposed group is more likely to develop outcome than group not exposed

Question 13

How is relative risk interpreted if RR<1?

Answer 13

Risk/incidence proportion is lower in exposed group

Exposed group is less likely to develop outcome than group not exposed

Question 14

Explain what OR=1 means.

Answer 14

No association between exposure and outcome

Question 15

What does OR>1 mean?

Answer 15

Positive association between exposure and outcome

Odds of exposure among those with outcome is greater than odds of exposure among those without outcome

Question 16

What does OR<1 indicate?

Answer 16

Negative association between exposure and outcome

Odds of exposure among those with outcome is less than odds of exposure among those without outcome

Question 17

Which range of odds ratios are generally indicative of a weak association?

Answer 17

Positive relationships (when RR>1): OR=1.01-1.50
Inverse relationships (when RR<1): OR=0.71-0.99

Question 18

Which odds ratios indicate a moderate association?

Answer 18

Positive relationships (when RR>1): OR=1.51-3.00
Inverse relationships (when RR<1): OR=0.41-0.70

Question 19

Which odds ratios indicate a strong association?

Answer 19

Positive relationships (when RR>1): OR=3.00 or higher
Inverse relationships (when RR<1): OR=0.00-0.40

Question 20

What does an odds ratio of 1, or confidence intervals spanning 1, mean?

Answer 20

Null hypothesis (no association) cannot be rejected