CHLH 274 FINAL EXAM 2025
QUESTIONS AND ANSWERS
Internal Validity - ANS when a study has proper selection of study groups and lack of error in
measurement
Internal Validity is concerned w/ - ANS measurement of exposure, measurement of
outcome, and association between exposure and disease
External Validity - ANS implies the ability to generalize beyond a set of observations to some
universal statement
Sources of Error in Epidemiologic Research - ANS random errors and systematic errors (bias)
Random Errors - ANS reflect fluctuations around a true value of a parameter because of
sampling variability
Factors Contributing to Random Error - ANS poor precision, sampling error, and variability in
measurement
Poor Precision - ANS Occurs when the factor being measured is not measured sharply;
precision can be increased by increasing sample size or number of measurements
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, Sampling Error - ANS occurs when the sample selected is not representative of the target
population; increasing the sample size can reduce the likelihood of sampling error
Variability in Measurement - ANS lack of agreement in results from time to time reflects
random error inherent in the type of measurement procedure employed
Systematic Errors (Bias) - ANS deviation of results or inferences from the truth, or processes
leading to such deviation
Factors that Contribute to Systematic Errors - ANS selection bias, information bias,
confounding
Selection Bias - ANS arises when the relation between exposure and disease is different for
those who participate and those who theoretically would be eligible for study but do not
participate.
Information Bias - ANS can be introduced as a result of measurement error in assessment of
both exposure and disease.
Recall bias (type of information bias) - ANS better recall among cases than among controls
Interviewer/abstractor bias (type of information bias) - ANS occurs when interviewers probe
more thoroughly for an exposure in a case than in a control
Prevarication (lying) bias (type of information bias) - ANS occurs when participants have
ulterior motives for answering a question and thus may underestimate or exaggerate an
exposure
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QUESTIONS AND ANSWERS
Internal Validity - ANS when a study has proper selection of study groups and lack of error in
measurement
Internal Validity is concerned w/ - ANS measurement of exposure, measurement of
outcome, and association between exposure and disease
External Validity - ANS implies the ability to generalize beyond a set of observations to some
universal statement
Sources of Error in Epidemiologic Research - ANS random errors and systematic errors (bias)
Random Errors - ANS reflect fluctuations around a true value of a parameter because of
sampling variability
Factors Contributing to Random Error - ANS poor precision, sampling error, and variability in
measurement
Poor Precision - ANS Occurs when the factor being measured is not measured sharply;
precision can be increased by increasing sample size or number of measurements
COPYRIGHT © 2025 BRAINBARTER ALL RIGHTS RESERVED 1
, Sampling Error - ANS occurs when the sample selected is not representative of the target
population; increasing the sample size can reduce the likelihood of sampling error
Variability in Measurement - ANS lack of agreement in results from time to time reflects
random error inherent in the type of measurement procedure employed
Systematic Errors (Bias) - ANS deviation of results or inferences from the truth, or processes
leading to such deviation
Factors that Contribute to Systematic Errors - ANS selection bias, information bias,
confounding
Selection Bias - ANS arises when the relation between exposure and disease is different for
those who participate and those who theoretically would be eligible for study but do not
participate.
Information Bias - ANS can be introduced as a result of measurement error in assessment of
both exposure and disease.
Recall bias (type of information bias) - ANS better recall among cases than among controls
Interviewer/abstractor bias (type of information bias) - ANS occurs when interviewers probe
more thoroughly for an exposure in a case than in a control
Prevarication (lying) bias (type of information bias) - ANS occurs when participants have
ulterior motives for answering a question and thus may underestimate or exaggerate an
exposure
COPYRIGHT © 2025 BRAINBARTER ALL RIGHTS RESERVED 2
