From: Leukaemia incidence among workers in the shoe and boot manufacturing industry: a case-control study
Cause or Source of Bias | Direction of the Effect |
---|---|
Accuracy of "Usual Occupation" on Death Certificate | Either (most likely toward the null) |
Only deceased individuals eligible as controls | Toward the null |
Lack of specific job titles | Toward the null |
Migration into and out of region | Toward the null |
No information on length of employment | Toward the null |
No information on specific chemicals used | Toward the null |