As our appraisals progressed, we encountered many challenges in interpretation that are common to the field of diagnostics evaluation. Most basic among these was confusion regarding the usage of the terms ''sensitivity'' and ''specificity,'' and the evaluations needed to measure these parameters [46] . The distinction between ''analytic'' performance characteristics, as opposed to ''diagnostic'' or ''clinical'' performance characteristics, is essential for properly assessing the validation of any assay, but it is particularly true in the field of molecular diagnostics. For NADTs, analytic sensitivity refers to the lowest concentration of target that can be detected, whereas analytic specificity measures the ability of the test to exclude undesired targets despite similar genetic sequences. In contrast, diagnostic or clinical sensitivity of a nucleic acid detection test refers to the appropriate identification of all patients carrying the agent, and diagnostic or clinical specificity describes the assay's ability to exclude uninfected patients. Clinical performance characteristics are subject to a number of factors, including the patient's disease status, variations in the concentration of the target throughout the course of illness, inhibition by other substances present in the specimen, sample quality, sampling variability, and specimen degradation. Generally, assays should be tested against a reference or gold standard. For tests of microbial detection, the reference standard typically is culture, but molecular diagnostics are often much more sensitive in detecting nucleic acid than is culture for viable organisms, leading to difficulties in interpreting the clinical relevance of false-positive results. The challenges of assessing diagnostic tests have been increasingly recognized in recent years. For instance, the Standards for Reporting of Diagnostic Accuracy initiative [47, 48] offers guidelines on the reporting of diagnostic studies, whereas the Quality Assessment tool for Diagnostic Accuracy Studies provides corresponding guidance on their evaluation [49] .