PHC 6001 EXAM 2 QUESTIONS WITH VERIFIED
ANSWERS 2025
What are the attributes of case controls studies? - correct-answer-observational
measures the occurrence of the outcome of interest in one or more cohorts
What are the measures for case control studies - correct-answer-estimate a ratio
measure of effect (IRR, RR, PR)
case control indications - correct-answer-rct or cohort not feasibleinterested in
many exposuresoutcome is rare/long latencywell documented exposure
datareadily identifiable base
case control advantages - correct-answer-handles multiple exposuresefficient for
rare outcomesefficient for outcome with long latencyrapid assessment of
outbreaks
case control limitation - correct-answer-inefficient for rare exposurescontrol
selection challenginghistoric exposure assessment difficult to ascertainsubject to
bias
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types of case control studies - correct-answer-prospective (case
ascertainment)retrospective (case ascertainment)nested
What is TROHOC fallacy? - correct-answer-controls should be as much like the
cases as possible expect with regard to exposure
role of case crossover studies - correct-answer-risk of outcome increased during
or for a brief time after exposuretransient effect of brief exposure on the
occurrence of a rare acute onset diseasemeasures short term risk rather than
cumulative risk
case crossover indications - correct-answer-exposure of interest is transient with
little carryover effecttime lag between exposure and outcome is brief
what are advantages for case crossover - correct-answer-between individual
confounding is preventedhandles exposures that are transient
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What are ecologic studies? - correct-answer-characterize exposure and outcome
across populationsoften used to international comparisonsunit of analysis is the
groupgenerally cannot draw causal conclusions
what is the advantage of ecologic advantages - correct-answer-hypothesis
generatingcheap and quickcan provide policy relevant information
what are the limitations of ecologic studies? - correct-answer-unable to link
exposure and outcome at the level of the individualtemporality unclearinability to
account for important confounding, or redefine/recode data for analysis
What are case series study and what is it used for? - correct-answer-made up of
multiple case report
suseful in recognizing new diseases
What are advantages of case series advantages? - correct-answer-identify new
diseasesuse available clinical dataprovide natural history of diseaseprovide rapid
hypothesis generation