Research Methods Flashcards

1
Q

What is a case report?

A

-Detailed description of an individual patient with unusual or rare condition/case
-leads to speculation about possible causes
ex thalidomide study, FAS (fetal alcohol syndrome), ether

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2
Q

What is a Case series?

A

Extension of case reports: cluster of individuals with same condition

ex. toxic shock syndrome from rely brand tampons (staph aureus)

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3
Q

What are ecological or cross sectional studies?

A
  • Descriptive or analytical
  • Descriptive if: no hypothesis, no specific exposure/outcome, no valid comparison groups
  • Population level measures (unit of analysis)
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4
Q

3 common types of analytical studies?

A

1-ecological or cross-sectional studies
2-case control studies
3-cohort studies

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5
Q

What is a descriptive study

A
  • Characterize outcomes (morbidity/mortality) by place-person-time, and have no a prior hypothesis
  • 2 types (case reports & case series)
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6
Q

Type 2 error = ?

A

= Beta, i.e. False negative rate

=When you do not reject the null hypotheis, when you should have (there is in fact a difference)

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7
Q

Type 1 error = ?

A

Alpha, false positive rate

Shows a difference, when in fact there isn’t one

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8
Q

Power = ?

A

Power = 1 - beta

Rate of telling the true difference

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9
Q

What is an ecological fallacy?

A
  • Making an association between 2 populations, when in fact at the individual level, there is no causation.
  • Ex assuming causation in a popn that has higher rates of obesity and diabetes than another, but may miss causation at an individual level
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10
Q

What is a cross sectional study (different than ecological)?

A
  • Assess exposure and outcome at the same time (in one time point)
  • Example are surveys
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11
Q

Limitation of a cross-sectional study?

A

Establishing temporality

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12
Q

Retrospective case-control study principles ? (2 ideas)

A
  • start by classifying subjects based on outcome status
  • look back in time for exposure status
  • uses ODDs RATIO (OR)
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13
Q

Can you measure relative risk in case control studies?

A

No, because you dont know the true population of those who were exposed.

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14
Q

Formula for OR (odds ratio)

A

OR = (a/b) divided by (c/d)

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15
Q

What are case control studies good for ?

A
  • RARE conditions

- Usually need a larger population to capture a condition if its RARE (in the case of a prospective cohort).

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16
Q

What type of bias affects case control studies in particular?

A
  • Recall bias

- Patients are more likely to recall an exposure (when there may not have been one), if they are diseased

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17
Q

Prospective cohort study?

A
  • Classify based exposure status (exp vs non exposed)

- Follow forward in time (looking for an outcome)

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18
Q

Advantage of a prospective cohort study? Disadvantage?

Example being Framingham study

A

adv - Establish temporality

disadvantage - Very costly

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19
Q

What does Relative Risk > 1 imply?

A

Implies a hazard

20
Q

RR

A

Implies protective factor

21
Q

What is RETROSPECTIVE COHORT study?

A
  • historical cohort, where data is already collected

- existing data sources (eg ICES)

22
Q

What is ICES data?

A
  • Institute for Clinical Evaluative Sciences

- Health admin data, collected for purposes besides just health

23
Q

Two possible data sources for ICES?

A
  • Acute care (ICU, ER)

- Outpatient sources (rehab, clinics, etc)

24
Q

What is a nested case control study?

A
  • is a Hybrid study

- Case control study inside a Cohort study

25
Panel study?
-
26
Experimental study?
- Intervention in control of investigator | - RCTs and community trials
27
3 basic types of RCTS?
- preventive trials (primary intervention) - intervention trials (secondary intervention) - therapeutic trials (tertiary, cure vs improve prognosis)
28
Relative Risk formula?
RR = (a/a+c) / (b/b+d)
29
Odds ratio formula?
OR = ad/bc
30
Forrest plot used in what kind of study? | Size of dot refers to what?
- Meta analysis, or systematic review | - Sample size
31
Publication bias?
-People Publishing studies that only show positive results
32
Qualitative study design characteristics?
- hypothesis generating, not testing | - develop concepts that aid in understanding natural phenomenon through description
33
Common tools of qualitative designs?
- Interviews (semi structured, structured, unstructured) - gets rich info - build rapport
34
How is sampling done in qualitative studies?
``` Small (les than 50) Not probabilistic (too expensive to do so), nor representative ```
35
How do you analyze qualitative data?
- be systematic - theoretical constructs outlined - detailed methods
36
What is triangulation?
- Looking at multiple sources/views for the same data | - try to come up with one single unifying theory
37
What are Bradford Hill's Criteria for Causation?
- Strength of association (measured by RR, OR) - Correlation coefficient (dose response, does Y increase with X) - Consistency - Temporality
38
Other Hill criteria (5)?
- Specificity (effect has only one or a few causes) - Biological plausibility - Coherence (with other knowledge, no competing theories) - Experimental evidence -analogy (similar phenomenon)
39
What is confounding?
Confounder related to exposure and outcome, but not directly in a causal pathway
40
Famous example of a confounder?
- HRT (estrogen, progesterone) - Early studies suggested that people on HRT had lower CVS outcomes - Later studies showed the opposite, initial studies were in HCW
41
Example of confounding factors in link between obesity and heart disease?
SES, inactivity, built environment | they are outside of causal pathway
42
What is a mediator (as opposed to confounder)? Use example of obesity and heart disease
- Clogging of arteries | - would be in causal pathway (i.e. mediator)
43
Moderating factors?
- Similar to mediating, is in causal pathway - interacts, potentiates, effect modifying - eg salt intake, fat intake, inactivity
44
Effect modification?
Multiplicative effect, not additive | in causal pathway
45
When can you control for confounding?
Before the study starts (study phase), and | After the study starts (analysis phase)
46
3 ways in the study phase, to control for confounding?
- randomization - restriction - matching
47
Controlling for confounding in the analysis phase?
Multivariable analysis (multiple confounders) Linear regression Logistic regression