Answers 2026 Updated.
Define epidemiology - Answer The study of the distribution and determinants of health-
related states or events in specified populations, and the application of this study to the control
of health problems.
Define demography - Answer The science of human populations and is concerned with
population size, density, characteristics, and change
Functions of Epidemiology - Answer public health surveillance
- ongoing systematic collection, analysis, interpretation
field investigation
- coordinated effort to better understand and respond to a problem
analytic studies
- beyond descriptive studies-valid comparison group
evaluation
- relevance, effectiveness, efficiency, and impact of response activities
linkages
- can not work alone
Epidemiologic Triad - Answer host, agent, environment
- model of disease causation
Descriptive measure of health - Answer incidence - specified period of time
prevalence - snapshot
morbidity
mortality
demographics
, Rate of infection = - Answer [(the number of infections)/(the number of those in a population
that are at risk of infection)] x K
(where K is a constant (usually 1,000 , 10,000 , or 100,000)
The five W's of descriptive epidemiology. - Answer What? diagnosis or health event
Who? person(s) affected
Where? place(s) community or global
When? Time, repeated? changes over time?, first time?
Why/how? causes, risk factors, mode of transmission - distribution frequency - the number of
health events and the relationship to the size of the population
pattern - occurrence by time place and person
determinant - what causes or influences
relative risk ratio and what is says - Answer RR= (incidence rate among those
exposed)/incidence of those not exposed)
if the exposed population is higher than the rate of the non-exposed population, if so how many
times
high RR suggest that the factor is a risk factor
Odds ratio - Answer prospective data not always available - retrospective data analysis-odds
ratio helps approximate the risk
contigency (or 2x2) table
experimental study design in epidemiology - Answer clinical trials- more specific
community trials - interventions within a community
what are the observational study designs used in epidemiology? - Answer Cohort study
Case control study
Cross-sectional study
What is a cohort study? - Answer preplanned following subset of population over a lifetime,
to see how they are impacted and the prevalence of the disease