Measurement Uncertainty in TESTING - ISO/IEC 17025

Explore basic statistical concepts, including mean, deviations from the mean, variance, and standard deviation, with practical Excel calculations and degrees of freedom for samples.

The lecture covers components of measurement uncertainty in testing under ISO/IEC 17025, distinguishing random (type A) from systematic (type B) factors, with repeatability and reproducibility used to quantify uncertainty.

Examine how uncertainty components in testing relate to different statistical distributions. Explore normal, rectangular, triangular, and uniform distributions and how a divisor estimates each contribution.

Estimate standard uncertainty from component contributions in ISO 17025 testing, using normal, rectangular, triangular, and u distributions. Learn about repeatability, reproducibility, calibration certificates or CRM, and practical calculations with examples.

Examine how to estimate standard uncertainty components in testing, using pH and tensile strength examples to illustrate repeatability, calibration certificate uncertainty, resolution, bias, and handling units of different types.

Define the mathematical model, estimate standard uncertainties for all characteristics, combine them into a combined standard uncertainty, and compute expanded uncertainty at 95% confidence for reporting.

Learn to compute uncertainty budgets for tests with the same units, identifying repeatability, instrument and CRM contributions, and report expanded uncertainty at 95 percent confidence.

Explore measurement uncertainty in testing with components of different units, using mathematical models, type a and type b uncertainties, and three conversion techniques for combined results at 95 percent confidence.

Explore measurement uncertainty in mechanical testing using a different-units components example. Compute ultimate tensile strength from gauge diameter and force, and build an uncertainty budget under ISO/IEC 17025.

Learn how to convert component uncertainties with different units into the final measurement in mechanical testing, using sensitivity coefficients and differential calculus, for measurement uncertainty in testing under ISO/IEC 17025.

Learn how to combine relative uncertainties for components with different units using the relative uncertainty method in mechanical testing, including exponent weighting and the root-sum-square approach.

Compare three methods of converting components of standard uncertainty to a final quantity for estimating EMU in different units, highlighting applicability, mathematical calculation, differential equation approaches, and relative standard uncertainty.

Analyze elongation measurements in mechanical testing using gauge length and vernier calipers, compute percent elongation, and discuss relative and differential uncertainty methods.

Learn how chemical testing handles multiple units and uncertainty sources—from primary standard preparation to pipette and instrument measurements—through a hydrochloric acid concentration example.

Demonstrate chemical testing with different units using HPLC to determine an acid in food, build calibration curve, perform dilutions, and assess measurement uncertainty.

Explore how GC-MS using a bracketing method estimates concentration uncertainties, combining weighing, purity, flask volume, temperature, and repeatability into a final standard uncertainty for a 50 micrograms per milliliter calibration.

Derive a coverage factor for unreliable input quantities by considering 95% confidence, normal vs t distribution, and calculating the effective degrees of freedom for ISO/IEC 17025.

We discuss measurement uncertainty in conformity assessment and the decision rule under ISO 17025. The rule must be defined, agreed with the customer, and reported with the associated confidence level.

Explore how measurement uncertainty applies to laboratory activities, including retesting, recalibration, and comparing averages within expanded uncertainty limits. Discuss microbiological testing exceptions, uncertainty budgets, and root cause analysis for improvement.

Build the mathematical model of the measurement process, estimate standard and expanded uncertainties, and apply unit conversion methods with Excel examples for ISO/IEC 17025 testing.