🔗 Carl Heneghan: Why autism can't be diagnosed with brain scans | Science | guardian.co.uk
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How the brain scans results are portrayed is one of the simplest mistakes in interpreting diagnostic test accuracy to make. What has happened is, the sensitivity1 has been taken to be the positive predictive value2, which is what you want to know: if I have a positive test do I have the disease? Not, if I have the disease, do I have a positive test? It would help if the results included a measure called the likelihood ratio (LR), which is the likelihood that a given test result would be expected in a patient with the target disorder compared to the likelihood that the same result would be expected in a patient without that disorder. In this case the LR is 4.5. We've put up an article if you want to know more on how to calculate the LR.