Measurement Uncertainty: distribution_divisors
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 |
|---|---|---|---|---|---|---|---|---|---|---|
| distribution_divisors | normal_k2 | 95 | 2 | normal | 2 | 95.45 | pct | Normal distribution with coverage factor k=2: standard uncertainty = U_expanded / 2; used for calibration certificate values | 2 | Distribution_Divisor |
| distribution_divisors | rectangular_distribution | 57.7 | 1 | rectangular | 1.732 | 57.74 | pct | Rectangular (uniform) distribution: standard uncertainty = half-interval / sqrt(3) = half-interval / 1.732; used when only limits known (resolution, tolerance specs) | 1.732 | Distribution_Divisor |
| distribution_divisors | triangular_distribution | 65.7 | 1 | triangular | 2.449 | 65.7 | pct | Triangular distribution: standard uncertainty = half-interval / sqrt(6) = half-interval / 2.449; used when midpoint more likely than extremes | 2.449 | Distribution_Divisor |
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