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Summary of sources of error, bias parameters, and assigned distributions used in the two bias analyses |
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| Source of potential error |
Bias parameters |
Assigned distributions |
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| Alachlor Bias Analysis |
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| 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 |
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| Glyphosate Bias Analysis |
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| 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 |
Lash Journal of Occupational Medicine and Toxicology 2007 2:15 doi:10.1186/1745-6673-2-15 |
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