Lecture 3

Question 1

What are the 6 Bradford hill criteria ?

Answer 1

Consistency
Biological plausibility
Dose-response
Temoprality
Strength of the relationship
Reversibility

Question 2

Consistency

Answer 2

if other studies in diff pops, at diff times, using diff methodologies find the same association it is more probable that the relationship is causal

Question 3

Biological Plausibility

Answer 3

does the association make biological sense? Does it with with the natural history of the disease?

Question 4

Dose-response

Answer 4

if increased levels of exposure lead to greater frequencies of the outcome it is more probable that the relationship is causal. Does not have to be cont there can be a threshold

Question 5

Temporality

Answer 5

if an exposure causes an outcome it must precede the outcome. This is the most important

Question 6

What is the most important bradford hill criteria?

Answer 6

temporality

Question 7

Reversibility

Answer 7

if you take away the exposure do you see a reduction in the outcome. THis is not always possible to assess at the indv level
If an individual with lung cancer quits smoking their lung cancer might not go away but if you studied cancer incidence over the last 50 years as smoking rates have declined you would find that lung cancer incidence is also decling

Question 8

What must you do to determine a relationship is causal

Answer 8

bradford hill criteria

Question 9

Formulating a research question
SMART questions

Answer 9

specific - nuts and bolts
measurable
answerable- do you have the resources available
relevant-scientific community and to you
time- fit the frame in which you have to answer it

Question 10

Elements to consider for specific questions

Answer 10

The PI(E)COD method

Question 11

PI(E)COD

Answer 11

P: pop of interest
I: intervention? (if appropriate)
E: exposure of interest (if app)
C: control or comparison group
O: outcome?
D: Study design?

Question 12

Ecological variables are properties of ____, _____, or_____

Answer 12

groups, organizations, places

Question 13

What are the 3 types of measures in ecological studies?

Answer 13

Aggregate
Environmental
Global

Question 14

Aggregate measures

Answer 14

summaries derived from individuals ina group (proportion of children in a household, median income)

Question 15

Environmental measures

Answer 15

physical characteristics of a place (pollution level, hours of sunlight)

Question 16

Global measures

Answer 16

Group level attributes with no distinct individual level analog (pop density, the availability of the healthcare system, the existence of traffic laws) Everyone in the group is subject to the same global measures

Question 17

Ecological fallacy

Answer 17

associations observed at the aggregate level do not reflect associations at the individual level

Question 18

Oilers and Flames example of the ecological fallacy

Answer 18

if the edmonton oilers were performing worse than the calgary flames across the NHL season it would be an ecological fallacy that all edmonton oiler players are worse players than all calgary flames players

Question 19

Atomistic fallacy

Answer 19

The opposite of the ecological fallacy where one assumes that associations found at the individual level also hold true at the group level

Question 20

3 pros of ecological studies

Answer 20

low cost
sometimes variables are impractical to measure at the individual level
sometimes the effect of interest is at the ecological scale (policy level effects)

Question 21

4 cons ecological studies

Answer 21

the temptation to extrapolate group effects to the individual (ecological fallacy)
issues in combining data sources
Temporal ambiguity. exposure or outcome first
Migration across groups. If individuals migrate from one group to another over the course of the study

Question 22

Is there as statistical test for causation?

Answer 22

no

Question 23

Causal associations

Answer 23

A change in frequency of the exposure causes a change in frequency from the outcome

Question 24

A necessary cause is ____ for an outcome to occure

Answer 24

required

Question 25

A sufficient cause

Answer 25

outcome may cause exposure but may not be the only cause