Exam 2 Flashcards
Exposure
Outcome
point prevelance
number of people with an event at a specific time / whole population
period prevelance
people who develop disease (including all that died or left) / average pop at beg and end or population size at middle
population at risk
cumulative incidence
number of new cases / total number of people at risk
incidence rate
number of new cases / number of people at risk * time frame
person-time
sum of time at risk in each cohort (observed until outcome, censoring occurs)
proportion
numerator included in the denominator
rate ratio
compares the incidence rates of two groups
stable population
limited number people exiting and entering the group over the time period
unstable population
people leave, die, opt out often
incidence
new cases
prevalent cases
all current cases
Disease duration
time with disease
study midpoint
halfway during the study
recurrent outcomes
an outcome that can occur more then once in the same individual
morbidity
state of having a disease
mortality
number of deaths
burden of disease
measures impact of health problems in terms of cost, mortality etc.
Mortality rate
percentage of population that has died in that specific time period
cause-specific mortality
percentage of the population that have died due to a specified cause
group-specific mortality
percentage of a specific population of interest that has died over a specified period
proportionate mortality
percentage of total deaths due to a specific cause
case fatality rate
number of deaths from given disease / number of people who have the given disease
descriptive study
qualitatively describes – good for making hypothesis
case report
weakest level of evidence, good at new and rare diseases, sort of surveillance
case series
more patients, focused on characteristics of groups, retrospective or prospective, common diseases, number 2
hypothesis
state exposure and outcome relationship, magnitude and direction, testable
analytic study design
tests hypotheses – observational and experimental
ecologic
group level data are used for exposure outcome relationships, single point of time, cheap + easy, weak
aggregate
group level, environmental measures
unit of analysis
aggregation bias
bias that occurs because of an association between variables that does not exist at an individual level
cross sectional study
number 3, snap shot of population at a single point of time, exposure and outcome at the same time, participants sampled regardless of exposure status
target population
complete set of people to whom we want to apply to the study
study sample
a subset of target population assumed ot be representative of target population
exchangeability
if the disease experience would be the same for exposed if they were unexposed
reverse causation bias
outcome is a mistake as the cause of the exposure
case control
participants are selected on whether they have the outcome,
primary study base
recruit from an existing sample – nested, incidence outcomes
secondary study base
not well known, cases are identified , prevalent outcomes
control selection
population, neighborhood, hospital, friend, dead
density sampling
define a risk set (everyone at risk at a specific time), case and controls are matched, primary base,
case-cohort sampling
primary base, select all cases, select at beginning of cohort, number of controls doesn’t have to be equal, cases can also be controls
cumulative sampling
secondary study bases, sample at end of follow up
cohort study
best other than randomized trials, follow a group at risk and compare development of outcome, can be open or closed, concurrent or non-concurrent
base population
primary or secondary
self-selected exposure
closed cohort
no new members, time scale is same for all, defined by an event
open cohort/dynamic cohort
defined by a state, can exit enter and re-enter, duration can vary
cohort membership
prospective cohort study
investigator begins at the beginning of the study
non-concurrent cohort study
begins at end of the study and works backwards
follow-up
time between beginning and end
special exposure cohort
based on a specific exposure status, exam other exposures
general population cohort
independent of exposure status (examine many exposures)
baseline
start of follow-up time
active follow-up
frequent contact with participants
passive follow-up
linkage of existing registries
