Table 3.

Two-way table for calculation of efficiency valuesa

PCR resultNo. of samples that were culture or direct smear and/or antigen detection
PositiveNegative
Positive49 (a)1 (b)
Negative4 (c)24 (d)
  • a Sensitivity = a/(a + c) = 0.93, specificity = d/(b + d) = 0.96, positive predictive value = a/(a + b) = 0.98, negative predictive value = d/(c + d) = 0.86.