CLASS 61 AND 62: SYSTEMATIC AND RANDOM ERRORS Flashcards
Systematic and random errors: lack of validity and lack of precision
Contrafactual model
Define the type of error
SELECTION BIAS: inadequate selection at study inception
Healthy worker bias is a typical…
Selection bias: inadequate selection at study inception (COHORT STUDIES)
Neyman’s Fallacy, donde se escogen los casos prevalentes en vez de los incidentes, tiende a UNDERESTIMATION y es un …
SELECTION BIAS: inadequate selection at study inception (CASE-CONTROL STUDY)
If we do a case-control study in a hospital, what bias could appear?
BERKSON BIAS: selection bias of inadequate selection at study inception (case-control).
Prob. admission for exposed and unexposed cases and controls is ≠ and given by a characteristic related to the exposure.
Explain this type of bias
SELECTION BIAS: lost to follow-up (cohort study). There is underestimation, there is higher prevalence of smoking in the non-exposed group.
Explain this bias
SELECTION BIAS: missing values in the data set (cohort study). There is underestimation.
Tenemos menos fumadores en grupo expuesto.
SELECTION BIAS DIAGRAM
Bias with same proportion of persons badly classified with respect to the other variable
NON-DIFFERENTIAL INFORMATION BIAS
Bias in which we have different proportion of persons badly classified with respect to other variable
DIFFERENTIAL INFO BIAS
Define the type of bias
DIAGNOSTIC MIGRATION BIAS (WILL ROGERS) : Differential information bias of exposure in a cohort.
Repaso information and selection bias
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