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Six methods for defining normal in biomedical science*. |
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| method |
Properties of the clinical data, sign, or test |
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| Gaussian |
The statistical distribution of the data is known to be normal in persons without the disease. |
| Percentile |
Test result lies within a certain percentile of the possible range of results. |
| Diagnositic |
Research has established the probability that the target disease is present, for a given range of test results. |
| Therapeutic |
Research has shown that a specific treatment has a known probability of success for a given range of test results. |
| Risk factor |
Research has shown that presence of a risk factor increases risk of a specified outcome (e.g. morbidity or mortality). |
| Culturally desirable |
Carries strong socio-political expectations of normal appearance or behaviour. |
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Notes: *as described by Sackett et al (1997) and Smith (2002). | |
Abbott et al. BMC Musculoskeletal Disorders 2006 7:45 doi:10.1186/1471-2474-7-45 |
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