midterm

Question 1

Descriptive epidemiology

Answer 1

Classify according to person, place and time variables

Question 2

analytical epidemiology

Answer 2

explores causal hypotheses between exposures and health conditions

Question 3

Simple random sampling (SRS)

Answer 3

sample is selected using random processes

Question 4

stratified random sampling

Answer 4

to ensure adequate representation of minority groups that might be underrepresented in SRS

Question 5

convenience sampling

Answer 5

selecting individuals from easily accessible and available groups such as those who visit a specific clinic

Question 6

Systematic sampling

Answer 6

choosing via a systematic, predetermined approach from the sampling frame

Question 7

Cluster sampling

Answer 7

selecting groups of individuals

Question 8

Central tendency

Answer 8

in normal distribution, mean, median and mode are equal and situated at center of distribution with values symmetrically distributed around central point

Question 9

skewed distribution

Answer 9

mean, median and mode are often different- median is most accurate because it is resistant to outliers

Question 10

symmetric distribution

Answer 10

mean and median are equivalent- mean is preferred bc it is more stable/precise across different sample sizes

Question 11

Multimodal distribution

Answer 11

several peaks in frequency of data marking distinct groups/clusters within dataset (ex. Age-related changes)

Question 12

Epidemic curve

Answer 12

represents distribution of cases over specified time frame to identity patterns in disease outbreaks

Question 13

Dose-response curve

Answer 13

correlation between exposure and effect

Question 14

Incidence

Answer 14

number of new cases occurring in specific population in specific time period

Question 15

Prevalence

Answer 15

total number of existing cases in population at specific time, expressed as proportion, New cases and treatment advances that extend survival can boost prevalence

Question 16

person variables

Answer 16

Age, sex, race, socioeconomic status, marital status

Question 17

place variables

Answer 17

Morbidity and mortality influenced by geographic factors (ie life expectancy), urban vs rural, localized patterns of disease

Question 18

time variables

Answer 18

Secular trends (long-term changes in frequency of diseases), cyclic (seasonal) trends, point epidemics, clustering

Question 19

Criteria for causal relationship

Answer 19

Strength of association
Consistency
Specificity
Temporality- establishing that exposure occurs before health outcome
Biological gradient- depicting how increased exposure correlates with increased disease incidence
Plausibility
Coherence
Experimental evidence
Analogy in causality- comparison against established causal relationships

Question 20

Risk factor

Answer 20

Factors correlated with an increased likelihood of disease but are not sufficient on their own to cause it

Question 21

observational studies

Answer 21

ecological, case-control, cohort, cross-sectional

Question 22

experimental studies

Answer 22

clinical trials, field trials, community trials
Advantages: less prone to biases, control for confounding variables, causal relationships
Disadvantages: complex and costly, large sample size, ethical considerations, patient non-compliance

Question 23

bias

Answer 23

Systematic error that leads to deviation from truth

Question 24

Hawthorne effect

Answer 24

altered behavior bc know they’re being studied

Question 25

Recall bias

Answer 25

remembering exposure history

Question 26

Selection bias

Answer 26

selecting participants leads to misrepresentation of association between exposure and outcome

Question 27

ecological studies

Answer 27

estimate exposure levels for groups based on data from environment, applying same exposure level to all group members despite variations within group Advantages: broader context, conducted quickly with less resources because data is more readily available, useful when cant get individual level data Disadvantages: ecologic fallacy- correlations at group do not necessarily apply to individuals, overlook individual/personal behaviors and genetic predispositions

Question 28

case-control studies

Answer 28

cases have outcome/disease, retrospective approach Advantages: useful for studying low-prevalence conditions or rare diseases, fewer resources and quicker than traditional follow up studies Disadvantages: innacurate exposure measurements, representativeness of cases and controls may be uncertain, indirect estimates of risk, temporal relationships may not be clear

Question 29

cohort studies

Answer 29

tracks incidence overtime following cohort that shares common characteristic Fixed- individuals classified as exposed or unexposed at specific baseline time and followed Dynamic- continuous recruitment of new eligible candidates over time- inds may shift from unexposed to exposed group Advantages- evaluating incidence rates, direct observation of risk, relationship between exposure and outcomes over time, uncommon exposures or diseases with clear temporal relationships between exposures and outcomes Disadvantages- costly and time consuming, not useful in rare conditions, planning and tracking large groups, non-participation may affect demographics

Question 30

cross-sectional studies

Answer 30

examines defined population or random sample at specific point in time- assessing both presence of disease and potential determinants, mainly descriptive (not causal relationships) Advantages: snapshot, inexpensive and easy bc do not follow over time Disadvantages: establishing causal, controlling for confounding variables, accurate reporting of exposure by patients, selection bias, length bias

Question 31

clinical trials- randomized controlled trials (RCTs)

Answer 31

phase 1 tests safety, phase 2 immune responses and phase 3 randomization randomly allocated into test and control groups

Question 32

field trials and community trials

Answer 32

involve healthy individuals at risk, data collection in natural settings, evaluate intervention designed to prevent diseases involve groups, can be harder

Question 33

environmental epidemiology

Answer 33

etiology (causes/origins), natural history, health status of pop, effectiveness of interventions, geographic focus

Question 34

Natural history of disease

Answer 34

Pathological onset, presymptomatic stage, clinical stage Prognosis- predicting likely course of disease Efficacy- benefits of treatment under ideal conditions Effectiveness- benefits in real-world clinical settings (RCTs)

Question 35

dose-effect/dose-response relationship

Answer 35

Does-effect identify which adverse effects should be prioritized for prevention Dose-response to determine what constitutes acceptable level for exposure

Question 36

directed acyclic graphs (DAGs)

Answer 36

relationships/causal links (arrows) between variables (nodes), no sequence of arrows forms a closed loop, if 2 or more variables share same cause ("parent" cause should be included), unmeasured confounding/cause (arrow pointing both directions between 2 nodes)