ABSTRACT
Epidemiological Assessment Studies 103
Numerically, consider a study of 500 cancer cases and 500 controls. If 130 cases were exposed to ELF field and 370 were not exposed, the odds of being exposed in cases is 130/370 = 0.35. If 130 controls were also exposed, the odds of being exposed in controls is also 0.35. Accordingly, the OR will be 1, which means negative association between ELF field and cancer.
