&gt;  If you can separate the population into &quot;definitely diabetic&quot;, &quot;definitely not diabetic&quot;, and &quot;needs more testing&quot; quickly and cheaply, that&#x27;s a win.<p>That&#x27;s the fundamental problem. It turns out with a reasonably accurate test, a low incidence rate, and a large population, the &quot;definitely X&quot; class will be filled with people who <i>aren&#x27;t actually X</i>. Going back and trying to separate the two ends up costing more and causing more harm to the non-Xs then just waiting until there&#x27;s a problem. I&#x27;d encourage you to take a look at the link I posted since it takes a very clear look at the problem in the context of mammograms and breast cancer.