Comparison Between Ring Trials and Proficiency Testing

Introduction

In the field of laboratory quality assessment, the terms Ring Trial (interlaboratory test or ring test) and Proficiency Testing (aptitude test or competency test) describe exercises that compare results among different laboratories. Although both aim to improve the accuracy and reliability of analyses, their objectives, methodologies, and applications differ.

Ring Trials focus on the harmonization and validation of methods, whereas Proficiency Tests primarily assess the competence of laboratories.

Definition and Characteristics

A Ring Trial is an interlaboratory test in which multiple laboratories analyze the same sample under controlled conditions and follow a standardized protocol. Controlled conditions are the key on the difference against to proficiency testing, and therefore, they do not have the same objective.

Ring trials primary objective is to evaluate variability among laboratories and improve the reproducibility and precision of an analytical method. Ring Trials are commonly used in the validation phases of new methods or in studies aimed at harmonizing analytical techniques (example, CEN/TC 216). A key feature of Ring Trials is that the laboratory conditions should be as similar as possible to minimize the influence on the robustness evaluation of the method to be improved (test suspensions, culture media, specific test conditions (test surfaces, reference products, etc.) This approach helps identify systematic variations and allows methodological adjustments to standardize procedures.

On the other hand, Proficiency Testing is a comparative assessment designed to evaluate a laboratory’s ability to perform or technical competence in specific analysis. In this case, the organizers provide samples with known values—concealed from participants—and the results obtained are compared against reference values or those of other laboratories, each laboratory uses its own specific conditions since the objective of the test is to evaluate whether it is competent to perform the test. This type of evaluation is a common requirement for laboratory accreditation, particularly in compliance with standards such as ISO/IEC 17025. Unlike Ring Trials, Proficiency Tests do not assess the method itself but rather how accurately a laboratory applies its analytical procedures.

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