How do you perform measurement uncertainty analysis for a temperature measurement system?

Uncertainty analysis per GUM (Guide to Uncertainty in Measurement) involves identifying all uncertainty sources: sensor accuracy, calibration standard uncertainty, environmental effects, self-heating (RTD), lead wire resistance, transmitter accuracy, A/D conversion, and repeatability. Calculate each component as standard uncertainty (divide specification by appropriate divisor - 2 for 95% confidence, sqrt(3) for rectangular distribution), combine using RSS (root-sum-square) for uncorrelated sources, and apply coverage factor (k=2 for 95% confidence) for expanded uncertainty. Document uncertainty budget for traceability and compliance.