Inference on the symmetric-range accuracy.

The symmetric-range accuracy A of a sampler is defined as the fractional range, symmetric about the true concentration, that includes a specified proportion of sampler measurements. In this article, we give an explicit expression for A assuming that the sampler measurements follow a normal distribution. We propose confidence limits for A based on the concept of a 'generalized confidence interval'. A convenient approximation is also provided for computing the confidence limit. Monte Carlo evaluation indicates that the proposed approaches are very satisfactory even for small samples. The statistical procedures are illustrated using an example involving carbon monoxide monitoring.