Biostatistics 2025|COMPLETE EXAM TEST
(questions and verified answers)
FREQUENTLY MOST TESTED QUESTIONS
|already graded A+|100% passed!!
-Frequency of *disease* and frequency of* risk-
related factors* are assessed in the *present*.
-Asks, "What is happening?"
-I.e.: Particular 5-lipoxygenase genotype is
associated with a predisposition to atherosclerosis. -
<<answer>>..Cross-sectional study
-Compares a group of people *with disease* to a
group *without disease*.
-Measures *odds ratio* (OR).
-Patients with COPD had higher odds of a smoking
history than those without COPD -
<<answer>>..Case-control study
, -Compares a group *with a given exposure or risk
factor* to a group *without* such *exposure*.
-Can be *prospective* (asks, "Who will develop
disease?") or *retrospective* (asks, "Who developed
the disease)
-Measures *relative risk* (RR). -
<<answer>>..Cohort study
-Subjects are randomly allocated to a *sequence of
2 or more treatments* given *consecutively*.
-A *washout (no treatment) period* is often added
between treatment intervals to limit the confounding
effects of prior treatment. - <<answer>>..Crossover
study
-A type of *selection bias*.
-The *very sick* or very well (or both) are
erroneously *excluded* from a study.
-Excluding patients who have died will make
conditions look less severe. (DM has a protective
effect against MI) - <<answer>>..Prevalence-
Incidence bias
(Neyman's bias)
-Awareness of disorder alters recall by subjects
-Common in retrospective studies.