EPIDEMIOLOGY STUDY DESIGNS EXAM QUESTIONS AND ANSWERS

EPIDEMIOLOGY STUDY DESIGNS EXAM
QUESTIONS AND ANSWERS
Cross-Sectional Studies - ANSWER-Designed to determine what is happening right
now
Disease and exposure status are determined at the same time
Usually uses surveys and polls

Advantages of Cross-Sectional Studies - ANSWER-1. Inexpensive
2. No loss to follow-up
3. Used for public health planning

Disadvantages of Cross-Sectional - ANSWER-1. Only a snapshot
2. Can only determine prevalence
3. No information on cause-effect relationship

Prevalence Formula - ANSWER-PE=A/A+B PnE=C/C+D (Cross-Sectional)

Incidents Rate Formula - ANSWER-IE= A/A+B InE=C/C+D (Cohort Study, Clinical
Trials)

Odds Ratio - ANSWER-Odds of Exposure D= A/C
Odds of Exposure ND=B/D
OR=AD/BC (Case Control)


Cohort (Follow-Up) Studies consists of what two types of studies - ANSWER-
Prospective and Retrospective (Historical) Studies

Cohort Studies - ANSWER-Start With Exposed Group followed over a long period of
time to determine disease status
Calculating the incidents rate

Prospective Cohort Studies - ANSWER-Starts with present and collects into the future
Follow-up over long periods of time to see how disease has developed

Retrospective Cohort Studies - ANSWER-Data has already been collected in the past
Used to study Occupational or Environmental exposures
Look at current health records to see who developed the disease

Advantages of Prospective Cohort Studies - ANSWER-1. Can determine incidence
2. Good for Rare Exposures
3. Can study multiple Outcomes