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Table 1 Summary of sources of error, bias parameters, and assigned distributions used in the two bias analyses

From: Bias analysis applied to Agricultural Health Study publications to estimate non-random sources of uncertainty

Source of potential error Bias parameters Assigned distributions
Alachlor Bias Analysis
number of incident cancer cases positive predictive value
negative predictive value
trapezoidal distribution with minimum = 0.95, maximum = 1.0, and modes of 0.98 and 0.99
fixed at 0.99
mismeasurement of cumulative exposure cumulative exposure value assigned to each category triangular distributions with minimum and maximum equal to reported bounds of exposure category, and mode equal to its reported midpoint
allocation of cases to cumulative exposure categories number of cases in each exposure category multinomial centered on the number of cases observed in each category
rate ratios assigned to each exposure category log normal distribution mean equal to the log of the reported hazard ratio for each category and variance imputed from its 95% confidence interval
Glyphosate Bias Analysis
confounding of the association by all adjustment variables relative risk due to confounding trapezoidal distribution with minimum of 1 (no confounding after adjustment for age), lower mode of 1.18 (bound due to confounding by education), upper mode of 1.39 (all variables but state), and maximum 1.56 (all variables, including state)
exposure misclassification sensitivity and specificity of exposure classification triangular distribution with minimum 0.79, maximum 0.87, mode 0.82 based on agreement proportions