Final - Wk 9 (observational studies)

Question 1

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????

Answer 1

false

Question 2

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

Answer 2

case control

Question 3

Observational vs Experimental:

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

Answer 3

experimental

Question 4

Observational vs Experimental:

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

Answer 4

observational

Question 5

Observational vs Experimental:

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

Answer 5

observational

Question 6

Observational vs Experimental:

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

Answer 6

experimental

Question 7

Observational vs Experimental:

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

Answer 7

observational

Question 8

Descriptive vs Interferential:

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

Answer 8

descriptive

Question 9

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)?

Answer 9

interferential

Question 10

Descriptive vs Interferential:

– Which type of analysis cannot test a hypothesis?

Answer 10

descriptive

Question 11

Descriptive vs Interferential:

– Which type of analysis is used in testing hypotheses?

Answer 11

interferential

Question 12

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

Answer 12

• • exposure/risk factor

- - outcome

Question 13

What are the 2 outcome measures of cohort studies?

Answer 13

relative risk or risk ratio

Question 14

How do you interpret a relative risk ratio of:

– PR > 1

Answer 14

increased risk of outcome

Question 15

How do you interpret a relative risk ratio of:

– PR = 1

Answer 15

No risk of outcome

Question 16

How do you interpret a relative risk ratio of:

– PR < 1

Answer 16

Reduced risk of outcome

Question 17

What is the correct interpretation of a RR of 1.36?

Answer 17

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

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

Question 18

What is the interpretation of a RR of 0.80?

Answer 18

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

Question 19

What is the interpretation of a RR of 3.3?

Answer 19

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

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

Question 20

What type of cohort study is this:

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

Answer 20

Prospective

Question 21

What type of cohort study is this:

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

Answer 21

Retrospective

Question 22

What are 3 advantages of cohort studies?

Answer 22

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

Question 23

What are 2 limitations of cohort studies?

Answer 23

• • expensive

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

Question 24

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

Answer 24

cohort study

Question 25

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

Answer 25

• • with

- - without

Question 26

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

Answer 26

rare conditions

Question 27

Can case-control studies use what types of statistics?

Answer 27

odds ratio

Question 28

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.

Answer 28

odds ratio

Question 29

What does an Odds Ratio > 1 indicate?

Answer 29

OR > 1 = increased frequency of exposure

Question 30

What does an Odds Ratio = 1 indicate?

Answer 30

OR = 1 no change in frequency of exposure

Question 31

What does an Odds Ratio < 1 indicate?

Answer 31

OR < 1 = decreased frequency of exposure

Question 32

What is the purpose of cross-sectional studies?

Answer 32

look at prevalence

Question 33

What is a limitation of cross-sectional studies?

Answer 33

can’t tell whether exposure preceded disease

Question 34

What are 2 big problems of cross-sectional studies?

Answer 34

recall bias and self-reported bias

Question 35

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

Answer 35

comparison group

Question 36

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

Answer 36

at least 2 points in time