Final: Lecture 17 Flashcards
Recall / reporting bias
A differential level of accuracy/detail in provided information between study groups.
Exposed or diseased subjects may have a greater sensitivity for recalling their history.
Hawthorne effect
Individuals can report their “effects” of exposure, disease symptoms or treatment differently because they are part of a study.
Contamination Bias
control group accidentally receive the treatment or similar or are exposed to the intervention being studied
Compliance Bias
Groups being interventionally studied have different compliances.
Lost to follow-up bias
Differences between those that stay in the study, withdraw, or are lost to follow-up.
Diagnosis/Surveillance/Expectation Bias
Different evaluation/classification between groups.
Observers may have preconceived expectations.
“Hawthorne-Like effect”- from researcher
Interviewer/proficiency bias
Systematic difference in soliciting, record, or interpreting on the part of the researcher.
Healthy worker bias
can easily be seen in prospective cohort studies
Self-selection/responder/participant bias
those that volunteer to participate may be different from those who don’t want to participate.
Control selection bias
can easily be seen in case-control studies
Lead-time bias
can over estimate the benefit of screening
Length Bias
screening tends to identify cases with less aggressive forms of the disease.
Neyman Bias
type of selection bias that states that the probability of finding a case in a given time frame is related to mortality risk
Describe the importance of bias related to source, magnitude, and direction.
Source/type
Magnitude/strength: bias can account for a weak association (small RR/OR). not likely to account for a a very strong association.
Direction: Bias can over or under-estimate the true measure of association.
Non Differential misclassification
Error in both groups equally. For 2 category variable bias can move the measure of association (RR/OR) towards the null hypothesis
Ex. 0.3 to 0.7 or 1.9 to 1.2.
