u_cal = √(u_std² + u_rep²)。
u_cal = √(u_std² + u_rep²)。
| Item | Formula / Note | Source / Standard |
|---|---|---|
| Combined standard uncertainty | u_c = sqrt(u1^2 + u2^2 + ...) when the components are uncorrelated | JCGM 100:2008, Guide to the Expression of Uncertainty in Measurement (GUM) |
| Expanded uncertainty | U = k · u_c, usually with k = 2 for about 95% coverage | JCGM 100:2008, Guide to the Expression of Uncertainty in Measurement (GUM) |
| Type A and Type B evaluation | Type A uses statistical analysis; Type B uses other information such as certificates | JCGM 100:2008, Guide to the Expression of Uncertainty in Measurement (GUM) |
| Coverage factor | k is chosen from the required coverage probability and effective degrees of freedom | JCGM 100:2008, Guide to the Expression of Uncertainty in Measurement (GUM) |