| Risk factors - criteria |
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| n | Three criteria
need to be satisfied in order to identify |
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| a characteristic
as a risk factor: |
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| 1. the factor must be observed to covary
with the disease |
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| • | i.e., the
factor must be statistically associated with the |
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| development of
the disease |
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| • | or equivalently,
the frequency of disease must be |
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| observed to
differ by category or value of the factor |
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| 2. the presence of the risk factor ( or a
relevant change in |
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| the risk factor)
must precede occurrence of the disease |
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| ohcd603 |
| 17 |