Wk 5 - Capturing causes

Question 1

CAUSATION

i) can causation be measured? why?
ii) what does causation explicitly apply to?

Answer 1

i) no - it can only be inferred
- no research design allows direct causal relationships to be tested

ii) when action A causes outcome B

Question 2

CONFOUNDING

i) what is a confounder?
ii) name three things a confounder can be in relation to disease?

Answer 2

i) a nuisance variable that we are not interested in that affects/masks what we are interested in observing

ii) confounders can be
- a risk factor for a disease
- a preventative factor for a disease
- a surrogate or marker for a disease

Question 3

RESEARCH DESIGN

i) what does research design allow us to test?
ii) what is a hypothesis?
iii) what two things should a hypothesis be informed by?
iv) what are hypotheses used to infer?
v) name a study type that provides the best evidence for causal associations?

Answer 3

i) allows us to test hypothesis about cause effect relationships
ii) hypothesis - precise and testable statement of what the researcher predicts will be the outcome of the study
iii) informed by theoretical models of relationships between variables and previous observed data
iv) causal relationships
v) experimental study types eg clinical trials, preventative trials and community intervention trials

Question 4

KOCH POSTULATES

i) what were they about?
ii) what are the four postulates?

Answer 4

i) causal factors in infectious disease

ii) 1) MO must be found in abundance in all organisms with the disease but not in those without
2) MO must be isolated from diseased organism and grown in culture
3) cultured MO should cause disease when intro to healthy organism
4) MO must be reisolated from an innoculated diseased host and be identical to the original causative agent

Question 5

BRADFORD HILL CRITERIA

i) what is it about?

explain

a) strength of association
b) consistency
c) specificity
d) temporality
e) biological gradient
f) plausibility
g) coherence
h) experimental evidence
i) analogy

Answer 5

i) causal factors in sickness, injury and occupation
- make sense of disease that leads to sickness or injury

a) stronger assoc bet risk and outcome - less likely caused by other factors
b) replication of results by diff researchers in diff settings
c) exposure assoc iwth single specific disease
d) exposure precedes disease
e) increased exposure correspond to increased disease
f) rational scientific basis for exposure disease assoc
g) assoc consistemt with other knowledge on the topic
h) expiermental evidence reinforces causal relationship
i) assoc analogues to known causal relationship

Question 6

EVIDENCE OF HIERARCHY PYRAMID

i) give three types of study that lie at the top of the pyramid
ii) give two critisims of studies that are at the top? do they have a higher or lower risk of bias?
iii) give two studies that lie at the bottom? what may be under valued in these studies

Answer 6

i) top = meta analyses and systematic review, RCT, cohort studies

ii) over value or quantitive data, analysis and stat sig
- over value of internal validity
- lower risk of bias

iii) animal trials/invitro studies, case reports/opinions/letters
- under value of external validity (less evidence of real life patients, undervalue patient perspective and doctor judegement)

Question 7

name four things causal evidence does not do

Answer 7

1) doesn’t tell us what patients think or consider most important
2) doesnt tell us what its like to experience the disease/outcome
3) limited evidence for why or how things work
4) can be used to test and refine the theory but not generate it

Question 8

QUALITATIVE RESEARCH IN HEALTH AND MEDICINE

i) what type of agenda does it set?
ii) does it look at what/how/why or how many/much/frequently?
iii) name two complex/sensitive conditions it may be relevant to

Answer 8

i) sets a patient centred agenda
ii) looks at what how why
iii) relevant in - STIs, mental health problems (socially as well as medically experienced)

Question 9

SUMMARY

i) can casual associations be tested or observed?
ii) name kochs postulates (5)
iii) what is the bradford hill criteria? (9)
iv) does causal evidence tell us how or why things happen?
v) what does qualiatitve research explore? name two things that can be used to do this

Answer 9

i) no - can only be inferred
ii) pres of MO in diseased organism, MO isolated and cultured, intro of MO to healthy causes disease, MO can be reisol from intro healthy, disease organism can be ident and is the same as the original agent
iii) strength of assoc, consistency, specificity, temporality, biol gradient, plausibility, coherence, experimental evidence, analogy
iv) no
v) qual explores the how and why - using qual methods and data eg words, text, images