Measurement Uncertainty: coverage_factor_reference
GUM-compliant measurement uncertainty budget components and coverage factors for common engineering measurements. Covers Type A (statistical) and Type B (non-statistical) uncertainty sources with standard uncertainties, expanded uncertainties at k=2 (95%), and confidence levels for: length/dimension (caliper, micrometer, CMM, gauge block), mass (analytical balance, platform scale), temperature (Type K thermocouple, Pt100 RTD, IR pyrometer), pressure (Bourdon gauge, electronic transducer, liquid manometer), flow (orifice plate, turbine meter, Coriolis, ultrasonic transit-time), electrical (DMM, power analyzer), force (load cell), and torque (torque wrench). Also includes coverage factor reference rows (k=1/2/3, 68/95/99.7%) and distribution divisors (rectangular, triangular, normal, U-shaped). Per ISO/IEC Guide 98-3:2008 (GUM), NIST TN 1297, ISO/IEC 17025:2017.
| measurement type | uncertainty source | confidence level pct (%) | coverage factor k | distribution | divisor | expanded uncertainty k2 | expanded uncertainty unit | notes | standard uncertainty value | uncertainty type |
|---|---|---|---|---|---|---|---|---|---|---|
| coverage_factor_reference | k_1_645 | 90 | 1.645 | normal | 1 | 90 | pct | Coverage factor k=1.645: exactly 90% confidence level for normal distribution; used in some regulatory and safety analyses | 1.645 | Coverage_Factor |
| coverage_factor_reference | k_1_960 | 95 | 1.96 | normal | 1 | 95 | pct | Coverage factor k=1.96: exactly 95% confidence level for normal distribution (vs k=2 which gives 95.45%); preferred in statistics | 1.96 | Coverage_Factor |
| coverage_factor_reference | k_1_sigma | 68 | 1 | normal | 1 | 68.27 | pct | Coverage factor k=1: corresponds to 1 standard deviation; 68.27% confidence level for normal distribution | 1 | Coverage_Factor |
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