One of the following is not a characteristic of casual association-
Assosciations can be broadly grouped under 3 headings: Spurious association Indirect association Direct association, which consists of a) one to one causal association and b) multifactorial causation Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 95
Coherence
Specificity
Sensitivity
Biological plausibility
Epidemiology