Final - Wk 9 (observational studies) Flashcards Preview

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Flashcards in Final - Wk 9 (observational studies) Deck (36)
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1
Q

True/False:
– P-values can tell you if the mean difference b/w groups in a study is statistically significant and if there is bias present????

A

false

2
Q

Which type of study would be the best to assess associations in a rare disease?

A

case control

3
Q

Observational vs Experimental:

– Which study design category do investigators have control of variables?

A

experimental

4
Q

Observational vs Experimental:

– Which study design category do investigators not have control of variables?

A

observational

5
Q

Observational vs Experimental:

– Which study design category is best to use if there are many unknown factors?

A

observational

6
Q

Observational vs Experimental:

– Which study design category is best for investigating effect of single factors?

A

experimental

7
Q

Observational vs Experimental:

– Which study design category is often the preferred design for studies of adverse events.

A

observational

8
Q

Descriptive vs Interferential:

– Which type of analysis is useful mainly for prevalence and incidence - to characterize the population?

A

descriptive

9
Q

Descriptive vs Interferential:
– Which type of analysis is useful for any studies looking at cause and effect or associations among risk factors (like OR and RR)?

A

interferential

10
Q

Descriptive vs Interferential:

– Which type of analysis cannot test a hypothesis?

A

descriptive

11
Q

Descriptive vs Interferential:

– Which type of analysis is used in testing hypotheses?

A

interferential

12
Q

Cohort studies start with ____ and follow group over time to determine ____.

A
    • exposure/risk factor

- - outcome

13
Q

What are the 2 outcome measures of cohort studies?

A

relative risk or risk ratio

14
Q

How do you interpret a relative risk ratio of:

– PR > 1

A

increased risk of outcome

15
Q

How do you interpret a relative risk ratio of:

– PR = 1

A

No risk of outcome

16
Q

How do you interpret a relative risk ratio of:

– PR < 1

A

Reduced risk of outcome

17
Q

What is the correct interpretation of a RR of 1.36?

A

RRR = [ 1 - RR (1.36) ] x 100

– so RRR = risk of disease is increased by 36%

18
Q

What is the interpretation of a RR of 0.80?

A

RRR = [1 - 0.8] = 0.2 x 100 = 20%

– Risk of the outcome in the exposed group was reduced by 20% (or occurred 20% less) relative to the unexposed group

19
Q

What is the interpretation of a RR of 3.3?

A

RRR = [1 - 3.3] = 2.3 x 100 230%

– Outcome was 230% more likely to occur in the exposed group

20
Q

What type of cohort study is this:

– Cohort with/without risk factor of interest followed forward in time to record outcome?

A

Prospective

21
Q

What type of cohort study is this:

– Cohort is followed backward in time to examine risk factors present years in the past?

A

Retrospective

22
Q

What are 3 advantages of cohort studies?

A
    • show the natural course of a disease or condition
    • show how Tx work in “real world” settings
    • less possibility for bias
23
Q

What are 2 limitations of cohort studies?

A
    • expensive

- - cannot prove cause and effect as well as experimental designs like RCT

24
Q

Which is able to suggest cause and effect than case-control or cross-sectional studies:
– Case-control OR cross-sectional study OR cohort study

A

cohort study

25
Q

Case-control studies look at the difference between group ____ the disease/condition and one group ____.

A
    • with

- - without

26
Q

Case-control studies are useful for what type of conditions?

A

rare conditions

27
Q

Can case-control studies use what types of statistics?

A

odds ratio

28
Q

How many times more likely the odds of finding an exposure in someone w/ disease is compared to finding the exposure in someone w/o the disease.

A

odds ratio

29
Q

What does an Odds Ratio > 1 indicate?

A

OR > 1 = increased frequency of exposure

30
Q

What does an Odds Ratio = 1 indicate?

A

OR = 1 no change in frequency of exposure

31
Q

What does an Odds Ratio < 1 indicate?

A

OR < 1 = decreased frequency of exposure

32
Q

What is the purpose of cross-sectional studies?

A

look at prevalence

33
Q

What is a limitation of cross-sectional studies?

A

can’t tell whether exposure preceded disease

34
Q

What are 2 big problems of cross-sectional studies?

A

recall bias and self-reported bias

35
Q

If you want to evaluate effectiveness, you must have a ____ group.

A

comparison group

36
Q

In order to determine if cause precedes effect, measurements must be made when?

A

at least 2 points in time