The semiquantitative slide agglutination and single-tube Widal tests had positive predictive values (PPVs) of 25.0% (95% confidence interval, CI: 0.6–80.6) and 20.0% (95% CI: 2.5–55.6), respectively.

The prevalence rate of smear-positive tuberculosis was 145 per 100 000 (95% confidence interval: 110–180) assuming no tuberculosis in persons aged< 15 years.

This avoids the difficult problems to rank the interval Numbers, and views the decision scheme in a whole system to seek a positive and negative ideal scheme, thus being intelligible and operational.