Study Designs Flashcards

1
Q

Define ‘experimental study’.

A

Used to study the effect of an intervention.

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2
Q

Define ‘control group’.

A

Group that is given a placebo or an
alternative intervention.

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3
Q

Define ‘experiment group’.

A

Group that is given the intervention being tested.

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4
Q

Define ‘randomised control trial (RCT)’.

A

A study in which a number of similar people are randomly assigned to 2 (or more) groups to test a specific drug, treatment or other intervention.

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5
Q

What is RCT useful for?

A

Studying causal effect of an intervention.

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6
Q

Define ‘observational study’.

A

Observe the effect of a risk factor (or a treatment) without changing who is/isn’t exposed to it (unlike experimental
studies).
- Individuals are observed in a natural status

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7
Q

Why is observational study less reliable than experimental study?

A

Causal inferences derived from observational studies are not as strong as those from experimental studies.

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8
Q

Define ‘prospective study design’.

A

Researchers will follow and observe a group of subjects over a period of time to gather information and record the development of outcomes.

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9
Q

List three features of prospective studies.

A
  • Outcomes (even exposures) have not occurred when the study starts
  • Sample includes people exposed or un-exposed to a risk factor
  • Focus on the exposure groups
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10
Q

Define ‘retrospective study design’.

A

Uses existing data that have been recorded for reasons other than research.

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11
Q

List four features of retrospective studies.

A
  • Outcomes of interest have already occurred when the study starts.
  • Sample includes both cases & non-cases
  • Focus on the outcome groups
  • Data on exposures are from records or
    participants’ recall.
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12
Q

Define ‘longitudinal study design’.

A

Researchers repeatedly examine the same individuals to detect any changes that might occur over a period of time.

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13
Q

List three features of longitudinal studies.

A
  • Data on both exposures & outcomes are collected repeatedly, at multiple time points.
  • Can assess both between- and within-individual variations
  • Can study changes of a measure with age
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14
Q

Give two examples of longitudinal study.

A
  • Height growth in childhood
  • Decline of physical function over age
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15
Q

Why is longitudinal study an important study design in life course research?

A

It’s suitable for studying temporal effect.

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16
Q

Define ‘cross-sectional study design’.

A

The investigator measures the outcome and the exposures in the study participants at the same time.

17
Q

Why is cross-sectional study useful?

A

To study prevalence or inter-relationship
between measurements.

18
Q

Define ‘case-control study’.

A

Participants are selected for the study based on their outcome status. Thus, some participants have the outcome of interest (cases), whereas others do not have the outcome of interest (controls). The investigator then assesses the exposure in both these groups.

19
Q

What are the disadvantages of a case-control study?

A
  • Exposures contain gaps
  • Susceptible to bias
  • Cases recall better on exposures than non-cases
20
Q

What are the advantages of a case-control study?

A
  • Cost-effective
  • Useful for rare diseases
21
Q

Define ‘prospective cohort study’.

A

Individuals which share some common characteristics are followed-up
to monitor potential risk factors and outcomes. Risk factors are measured before the outcomes have occurred.

22
Q

Define ‘retrospective cohort study’.

A

Identify diseased subjects by interview or written records.

23
Q

Define ‘historical cohort study’.

A

Individuals are traced years later
* Birth records were kept by hospitals (or researchers)
* Go back in time to identify a cohort, establish their exposure
status at the time.

24
Q

What are the advantages of historical cohorts?

A
  • Useful when reliable records are available
  • Less costly
25
Q

What are the disadvantages of historical cohorts?

A
  • Often a huge gap in information
  • Selection & misclassification bias due to retrospective nature.
26
Q

What are historical studies used for ?

A

Early fetal programming work.