The concept of bias is the lack of internal validity or incorrect assessment of the association
between an exposure and an effect in the target population in which the statistic estimated …

Epidemiologists are aware that the estimated effect of an exposure can be biased if the
investigator fails to adjust for confounding factors when analyzing either a prospective or …

Epidemiology, being primarily an observational rather than experimental science, has often
encountered problems with measurement of the study variables, which are not under the …

The concept of the odds ratio is now wellestablished in epidemiology, largely because it
serves as a link between results obtainable from follow-up studies and those obtainable …

Random error (misclassification) in exposure measurements usually biases a relative risk,
regression coefficient, or other effect measure towards the null value (no association). The …

Lack of bias in the estimation of relative effect in epidemiologic studies depends on the
internal validity of the study. This paper conveys in graphic and tabular form the direction …

The problem of response bias in both retrospective (1-3) and prospective (4-6) studies has
been noted frequently. Previous discussions have generally focused on a specific example …

In studies in environmental epidemiology, exposure to harmful agents is often highly
variable in time and space. It is not usually possible to measure the relevant, personal …

It has been widelyaccepted that one reason for inconsistent or contradictory results of
epidemiologic studies is bias. Therefore, an appreciation of potential sources of bias has …

Abstract Interpretation of observational studies is difficult, particularly in cross-sectional
studies, because the direction of cause and effect may be difficult to assess Did the …