how do you diagnose someone with a medical condition

Question: how do you diagnose someone with a medical condition
- Keywords:
  diagnosis,
  disease,
  health,
  human,
  illness,
  medicine
Asked by hannah B to Iain, Hayley on 25 Jun 2015.
- Iain Bethune answered on 25 Jun 2015:
  
  The technique that most doctors use is called differential diagnosis. Based on the set of symptoms reported by the patient and the signs observed by the doctor, they draw up a list of possible causes, and give each of them a chance of occurring. E.g. if you show up with stomach pains there might be a 50% chance you have indigestion, 30% chance of viral infection or food poisoning, 10% chance of appendicitis, and 10% chance of cancer (these numbers are not correct, but I just made them up to illustrate the method). If the most likely cause is highly likely, then the doctor will treat you for that condition. If not, they will decide to carry out further tests which might rule out some of the possibilities.

Question: how do you diagnose someone with a medical condition