The health service

El cribado is a sieve. La criba is the wide flat sieve a farmer shakes to let the grain fall through and keep back the stones, cribar is to work it, and a screening programme is exactly that: everybody goes over the mesh once, and the few who do not fall through are looked at properly. English arrives at the same idea by way of another mesh, the screen that coal was once shaken against. In both languages the picture explains why a screening test is allowed to be rough — the sieve is not the diagnosis, it only decides who gets examined next.