Exam 1- Epidiemology

Question 1

Strength of association

Answer 1

association between exposure and outcome

Question 2

Temporality

Answer 2

MOST IMPORTANT; an exposure must precede the occurence of a disease

Question 3

Biological gradient

Answer 3

risk of disease being related to degree of exposure

Question 4

Plausibilty

Answer 4

biological plausibility of hypothesis, biological mechanism to explain

Question 5

Coherence

Answer 5

Should not conflict with what is known of natural history

Question 6

analogy

Answer 6

one drug causes a defect, similar will to…

Question 7

Specificity

Answer 7

LEAST IMPORTANT; exposure should lead to a single effect

Question 8

Experimental Evidence

Answer 8

Reduction in exposure is associated with reduction in risk and vise versa

Question 9

Prevalence

Answer 9

Number of EXISTING CASES at a specified time

Question 10

Incidence

Answer 10

number of NEW CASES

Question 11

Relative Risk

Answer 11

measure of association in cohort studies because incidence can be measured in them, how common disease is among the exposed

Question 12

RR=1

Answer 12

null association, no difference in disease between the two groups

Question 13

RR > 1

Answer 13

means exposure increases risk

Question 14

RR<1

Answer 14

exposure decreases risk

Question 15

Odds Ratio

Answer 15

measure of association in CASE CONTROL and CROSS-SECTIONAL studies; indirect estimate of RR as incidence cannot be measured in these studies; tells how common the exposure is among the diseased

Question 16

Can measure incidence

Answer 16

cohort studies

Question 17

cannot measure incidence

Answer 17

Case control and cross-sectional

Question 18

OR=1

Answer 18

no difference in exposure history between cases and controls

Question 19

OR<1

Answer 19

exposure history is less common

Question 20

OR >1

Answer 20

exposure history is more common among cases

Question 21

Attributable risk

Answer 21

absolute risk difference or the percentage of cases due to a given exposure

Question 22

how much long cancer can actually be attributed to smoking

Answer 22

attributed risk

Question 23

Attributable proportion

Answer 23

proportion of people who developed disease due to exposure

Question 24

Bias

Answer 24

a systemic error in conduct of study based on selection of groups not being comparable, differences in information collected from study groups

Question 25

Confounding

Answer 25

the observed relationship between the dependent and independent variables is due to a third varibale

Question 26

gray hair associated to heart disease, really it is

Answer 26

age- confounding variable

Question 27

counterfactual model

Answer 27

comparing the experience of a population exposed to a factor with the experience of the same population at the same time but without the exposure (can't, so use substitute population)

Question 28

ways to control confounding

Answer 28

- randomization, restriction - matching; forces distribution of matching factors to be identical in various study groups - analysis: look at the OR, multivariable analysis

Question 29

descriptive studies

Answer 29

Case reports, case series, and cross-sectional; | you cannot assert causation; not a true experimental study

Question 30

Case reports and case series

Answer 30

types of descriptive studies, with no controls so you cannot assert causation; not a true experimental study

Question 31

Cross sectional

Answer 31

a type of descriptive study; made at ONE POINT in time so temporality is NOT known and hence causation cannot be ascertained (think snapshot view)

Question 32

Cohort studies

Answer 32

follow exposed and unexposed people around, expensive, based on independent predictor variable; include prospective and Retro

Question 33

Prospective Cohort study

Answer 33

follow subjects without disease (see if they get it)

Question 34

Retrospective cohort study

Answer 34

both exposure and disease have happened in the past

Question 35

Case Control Studies

Answer 35

ID people with disease and suitable non disease individuals as controls (Retrospective design, must have controls with similar chance of exposure, Incidence CANNOT be measured)

Question 36

Experimental studies/clinical trials

Answer 36

researcher assigns exposure; these people provide highest level of epidemiological evidence; Blinding and randomization; includes validity (ext and int) and reliability

Question 37

Internal validity

Answer 37

study is done without methodological problems

Question 38

external validity

Answer 38

study accurately reflecting events that would occur in real situation

Question 39

Meta Analysis and Systemic Reviews

Answer 39

studies of studies; PROVIDE the HIGHEST level of confidence

Question 40

Provide the highest level of evidence

Answer 40

systemic reviews

Question 41

Co-relational/ecological

Answer 41

individual exposure level not available (study populations)-type of descriptive study