In testing laboratories, making informed decisions based on test results is crucial. The ISO/IEC 17025:2017 standard highlights the importance of using decision rules in this context. A decision rule is a protocol that laboratories follow to determine if a test result meets certain standards or specifications, like pass/fail or in-tolerance/out-of-tolerance.
When a customer requests a statement of conformity, it’s essential for the laboratory to define a clear decision rule. This rule takes into account the uncertainty of measurements, which is critical for accurate decision-making. The uncertainty must be considered to determine the likelihood that a test result truly conforms to or deviates from a specified standard.
For example, a lab tests a product to see if it contains a certain chemical within safe limits. The decision rule may state that the chemical’s concentration must be below a specific level, factoring in the uncertainty of the measurement. If the measurement, including its uncertainty, is below this level, the product passes; if not, it fails.
The choice of decision rule depends on the risk associated with incorrect decisions (false accept or reject) and the requirements of the test’s application. The laboratory must clearly communicate the chosen rule to the customer, particularly when it’s not inherent in the requested specification or standard. This ensures transparency and understanding between the laboratory and the customer about how conformity decisions are made
The laboratory must communicate the chosen decision rule to the customer for agreement, especially when it isn’t inherent in the requested specification or standard. This step ensures transparency and mutual understanding between the laboratory and the customer regarding how decisions on conformity are made.
In practice, this means laboratories must have a thorough understanding of their measurement capabilities and the associated uncertainties. They must be able to effectively communicate this information to customers, ensuring that all parties have a clear understanding of what the test results signify and how they are determined.
Decision rule is described in the following
Adhering to these guidelines helps maintain accuracy and reliability in laboratory testing, ultimately supporting quality decision-making and customer satisfaction.
In summary, the application of decision rules requires careful consideration of measurement uncertainty, the context of the test, and clear communication with customers.
About the Author
Dr. Sambhu Chakraborty is a distinguished consultant in quality accreditation for laboratories and hospitals. With a leadership portfolio that includes directorial roles in two laboratory organizations and a consulting firm, as well as chairman of IOL ( An ILAC stakeholder organisation), Dr. Chakraborty is a respected voice in the field. For further engagement or inquiries, Dr. Chakraborty can be contacted through email at director@iaqmconsultants.com and info@sambhuchakraborty.com. Additional resources and contact information are available on his websites,https://www.quality-pathshala.com and https://www.sambhuchakraborty.com , or via WhatsApp at +919830051583