Converting information to standard uncertainty
An assigned rectangular distribution on estimate±a gives u=a/√3, while a symmetric triangular distribution on the same interval gives u=a/√6.
Key knowledge
An assigned rectangular distribution on estimate±a gives u=a/√3, while a symmetric triangular distribution on the same interval gives u=a/√6. A certificate's expanded uncertainty U can be divided by its stated coverage factor k to recover its reported standard uncertainty; an interval without a distribution or coverage rule does not uniquely specify u.
Values and equations
u_rect=a/√3; u_tri=a/√6; u_certificate=U/k
- u_rect,u_tri,u_certificate,a,U
- Standard uncertainties, half width and expanded uncertainty; quantity unit
- k
- Dimensionless specified coverage factor
Conditions and scope
- a>0 and the stated probability model actually represents available information; certificate U and k have compatible definitions.
- Do not assume every tolerance is uniform, every interval is 95%, or every quoted limit is a standard deviation. Distribution reliability and parameter uncertainty need their own assessment.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
NIST TN 1297 (1994): Type B evaluation: Sections 4.2–4.6: quoted multiplier, rectangular and triangular standard uncertainty; conditional normal conversion qualified.
2026-10-10 · Independent AI editorial review: Independent root AI editorial review of all29 authored Measurement claims/conditions, displayed equations and37 origin relations. The original26 claims were read against41 primary source sections; all5 requested corrections and the3 affected source bindings were subsequently rechecked. Three actual scalar-nonlinear/vector/dynamic applications were read, independently differentiated or integrated, and checked against the specific additional source material described below. This is reference-content review, not human specialist certification, instrument certification or experimental replication. Full-field sign-off waits for the combined final conceptual matrix. Receipt: measurement-independent-content-review.1.
Entry details
Permanent link to this entry ↗- Record identity
- measurement-distribution-standard-uncertainty
- Revision
- university-core.1
- Structured reference record
- University core expansion