EPID 410 Final questions with verified
answers
false - correct answer ✔✔T/F: A cross sectional study of the relationship between blood type
and the risk of cataracts will produce misleading results because you cannot tell temporal
relationship between the exposure (blood type) and disease (cataracts)
confounder - correct answer ✔✔distorts the estimate of association between exposure and
outcome; perhaps reverse relationship
3 criteria:
1. must be a risk factor for outcome
2. must be associated with exposure
3. must not be an intermediate step in causal path between exposure and outcome
account for a confounder - correct answer ✔✔to remove the effect of the confounder on the
relationship between exposure and outcome
in most cases, cannot adjust unmeasured or unknown factors--must have cigarette smoking
behavior
cannot completely adjust for imprecisely measured factors
prevention strategies - correct answer ✔✔attempt to control confounding through the study
design itself
3 types:
, 1. randomization
2. restriction
3. matching
2 types of analysis strategies:
1. stratification
2. multivariate techniques
randomization - correct answer ✔✔attempts to ensure equal distributions of the confounding
variable in each exposure category
typically seen in RCTs
advantages of randomization - correct answer ✔✔convenient, inexpensive, permits
straightforward data analysis
disadvantages of randomization - correct answer ✔✔-need control over exposure and ability to
assign subjects to study groups
-need large sample size
-may not be applicable depending on study design
restriction - correct answer ✔✔practice of restricting your study sample based on various
factors
ex. only women, no men
may prohibit variation of the confounder in the study groups
ex. narrowing age category can eliminate age as confounder
answers
false - correct answer ✔✔T/F: A cross sectional study of the relationship between blood type
and the risk of cataracts will produce misleading results because you cannot tell temporal
relationship between the exposure (blood type) and disease (cataracts)
confounder - correct answer ✔✔distorts the estimate of association between exposure and
outcome; perhaps reverse relationship
3 criteria:
1. must be a risk factor for outcome
2. must be associated with exposure
3. must not be an intermediate step in causal path between exposure and outcome
account for a confounder - correct answer ✔✔to remove the effect of the confounder on the
relationship between exposure and outcome
in most cases, cannot adjust unmeasured or unknown factors--must have cigarette smoking
behavior
cannot completely adjust for imprecisely measured factors
prevention strategies - correct answer ✔✔attempt to control confounding through the study
design itself
3 types:
, 1. randomization
2. restriction
3. matching
2 types of analysis strategies:
1. stratification
2. multivariate techniques
randomization - correct answer ✔✔attempts to ensure equal distributions of the confounding
variable in each exposure category
typically seen in RCTs
advantages of randomization - correct answer ✔✔convenient, inexpensive, permits
straightforward data analysis
disadvantages of randomization - correct answer ✔✔-need control over exposure and ability to
assign subjects to study groups
-need large sample size
-may not be applicable depending on study design
restriction - correct answer ✔✔practice of restricting your study sample based on various
factors
ex. only women, no men
may prohibit variation of the confounder in the study groups
ex. narrowing age category can eliminate age as confounder
