POPM*3240 Midterm 2

What are the 3 main types of bias in epidemiological studies?

(a)  

In case controls, researchers will increase the amount of controls they have relative to their controls to increase (a)   , the chances of detecting a difference between groups and identifying a risk factor

In cohort studies, we want to ensure validity through selection of exposure positive & exposure negative groups. If participants are representative of the _____ population, external validity is present. If participants are representative of the _____ population, internal validity is present.

• study, target

• source, target

• target, study

• target; source

• source, study

Answer explanation

If a test is (a)   , it means that it has been tested in multiple populations and is known to measure what it is supposed to measure – this will reduce misclassification bias (classification using this method is probably more accurate)

Answer explanation

Which of the following biases is not of concern in cross-sectional studies?

• Detection bias

• Non-response bias

• Loss to follow up bias

• Confounding bias

• Recall bias

Answer explanation

Changes in screening and diagnostic methods over time results in which of the following biases?

• Detection bias

• Non-response bias

• Misclassification bias

• Confounding bias

• Loss to follow-up bias

Answer explanation

Risk ratio, odds ratio, and incidence rate ratio (measures of association) are useful for investigating (a)   , but are NOT as helpful for informing practice (e.g., clinical or public health practice)

E.g., Could have very high risk ratio (strong association at the factor level), but if the exposure is rare, it won’t contribute much to disease in a population - an example of this is the BRCA gene, which is rare, but there is a strong association between having the gene and having breast cancer

Which of the following epidemiological measures of association (MOA) can be used in all studies, making it the most common MOA?

• Incidence risk ratio

• Risk Ratio

• Odds ratio

Answer explanation

Match the study design

Groups:

(a) DESCRIPTIVE STUDIES

,

(b) ANALYTICAL STUDIES (Experimental)

,

(c) ANALYTICAL STUDIES (Observational)

• Case Series

• Case report

• Cohort studies

• Cross-sectional

• Randomized controlled trials (RCTs)

• Surveys

• Case-control

Answer explanation

Match the descriptive study type to the statement

Groups:

(a) Case Reports

,

(b) Case Series

,

(c) Survey

• Describe rare condition/unusual case(s)

• Does NOT describe the methodology of a questionnaire

• Presently, COVID-19 is not new and as such, this would exist for COVID-19

• E.g., first cases of COVID-19 were reported as an unknown pneumonia

• Using a tool to collect information from individuals in a population

• Prevalence of E. coli O157:H7 shedding in cattle (proportion of cows shedding this bacteria)

• Describes usual clinical course of a condition of interest

• Helps clinicians recognize pattern recognition of what they might look for and expect in cases

• This term describes a verb