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Table 1 Four phases for a forensic chemical method to describe its performance

From: Evaluation of forensic chemical method performances by phase tagging

Phase Stage Description and scope
I Pilot The method has been pilot tested using a small number of samples (n < 10). The findings are indicative of the suitability of the method for the intended purpose. At this stage, the method has been optimized but no proper data are in place to support its fitness. Some level of selectivity is usually achieved.
II Validated The method has been appropriately tested for its fitness in terms of selectivity, precision, linearity, accuracy, sensitivity, ruggedness/robustness, etc. depending on its purpose. The obtained findings are able to meet the minimum acceptance criteria set by the laboratory or by the scientific community at large.
IIIa Proven The validated method is further tested using contrived samples or a small set of real samples (n < 100) to test its performance. A high level of confidence is observed in the findings.
IIIb In-use The validated method is further verified using a large set of real samples (n > 100) on a routine basis to test its practicality in terms of interference and consistency.
IV Idyllic The method in use is employed in proficiency testing where the results are within the intended z-score.