A recent paper in the Journal of Clinical Microbiology (J Clin Micro Apr 1998-36-862/5) by Albadaleho et al, compared an automated essay for Hepatitis C Virus RNA against the gold standard usual approach, and was able to demonstrate that when the diagnosis was not in doubt the new method was equally sensitive and specific, both at very high levels. They therefore demonstrated efficacy. The advantage of the new method is not increased precision but the fact that it is automated and can also conduct other tests at the same time, with increased capital cost but reduced operating expense. The paper did not address how well the test would work when the diagnosis was not already known and so could not demonstrate positive and negative predictive values in the real world (effectiveness).