Clinical Prediction Rules can can be pretty useful tools (when used with a great subjective history and physical exam of course)
Take the CPR for Cervical Radiculopathy for instance (visit physiopedia for some videos)
If a patient is presenting with 3 out of these four signs there is a 94% specificity, and goes up to 99% with all four:
1) Cervical Rotation <60*
2) + Spurling’s Test
3) + Distraction Test
4) + Upper Limb Tension Test
Now that is some tasty specificity……
A Cup A Day 