PHC 6001 Final Exam Exam Questions with
Complete Solutions
dynamic and fixed cohort studies usually use __________ to measure disease frequency whereas
closed population fixed cohort studies use __________ to measure disease frequency
incidence rate; cumulative incidence
cohort studies are not efficient for rare exposures
when would you choose a case-control study? - dont have exposure data
- disease of interest is rare
- disease has long induction/latent period
- underlying population is dynamic
what are the three things you need to assess to determine the validity of a study? bias,
confounding, and random error
bias systematic error that results in an incorrect (invalid) estimate of the measure of
association and is primarily introduced by the investigator or study participants
, internal validity determining if the study was done without bias, confounding, or random
error
external validity determining if the study is generalizable to all populations
selection bias study subjects don't represent the target population
selection bias is most likely to occur in case control or retrospective cohort studies
in case control studies, control selection bias occurs when a researcher doesn't use the
same criteria for selection controls as for selecting cases
self-selection bias can occur if you have a case-control study that doesn't have high
participation rates if the decision to participate or not is related to the exposure and the outcome
surveillance bias occurs in case-control studies due to differential surveillance, diagnosis,
or referral of cases
Complete Solutions
dynamic and fixed cohort studies usually use __________ to measure disease frequency whereas
closed population fixed cohort studies use __________ to measure disease frequency
incidence rate; cumulative incidence
cohort studies are not efficient for rare exposures
when would you choose a case-control study? - dont have exposure data
- disease of interest is rare
- disease has long induction/latent period
- underlying population is dynamic
what are the three things you need to assess to determine the validity of a study? bias,
confounding, and random error
bias systematic error that results in an incorrect (invalid) estimate of the measure of
association and is primarily introduced by the investigator or study participants
, internal validity determining if the study was done without bias, confounding, or random
error
external validity determining if the study is generalizable to all populations
selection bias study subjects don't represent the target population
selection bias is most likely to occur in case control or retrospective cohort studies
in case control studies, control selection bias occurs when a researcher doesn't use the
same criteria for selection controls as for selecting cases
self-selection bias can occur if you have a case-control study that doesn't have high
participation rates if the decision to participate or not is related to the exposure and the outcome
surveillance bias occurs in case-control studies due to differential surveillance, diagnosis,
or referral of cases
