EPIB301 EXAM 2 ACTUAL QUESTION AND

EPIB301 EXAM 2 (ACTUAL / QUESTION AND

VERIFIED CORRECT ANSWERS LATEST UPDATED

Disadvantages of general population controls Time consuming, expensive, hard to contact and get cooperation; may remember exposures differently than cases

Reporting bias Occurs when a source has the required knowledge but we question his or her willingness to convey it accurately

Recall bias Cases may remember an exposure more clearly than controls

Poor recall Information or advice given to patients is easily forgotten.

Matched case control study A study in which the cases and controls havebeen matched (i.e., are selected to be similar)according to one or more criteria such as sex,age, race, or other variables.

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Odds ratio A measure of the association between frequency of exposure and frequency of outcome used in case-control studies

Risk vs odds

Risk: chances of something happening/chances of all things

happening

Odds: chances of something happening/chances of it NOT

happening

Problem and alternative approach

Problem: don't have resources s to get data on all subjects in a

population

Alternative: use surveillance databases

Strength of case control studies Efficient for rare diseases and diseases with long induction and latent period.

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Can evaluate many risk factors for the same disease so good for diseases about which little is known

Weakness of case control studies Inefficient for rare exposures

• Vulnerable to bias because of retrospective nature of study

• May have poor information on exposure

• Difficult to infer temporal relationship between exposure and disease

Ecological studies A study in which the units of analysis are populations or groups of people rather than individuals

Ex: nations, states

Ecologic comparison study Involves an assessment of the association between exposure rates and disease rates during the same time period

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