CCT-K7.2021

MEASURAND   Temperature of the triple point of water

NOMINAL VALUE 273.16 K

Degrees of equivalence represented by D_i = (x_I - x_R) and its expanded uncertainty U_i at a 95 % level of confidence, both expressed in µK.

CCT-K7.2021

MEASURAND   Temperature of the triple point of water

NOMINAL VALUE 273.16 K

Degrees of equivalence represented by D_i = (x_I - x_R) and its expanded uncertainty U_i at a 95 % level of confidence, both expressed in µK.

CCT-K7.2021

MEASURAND   Temperature of the triple point of water

NOMINAL VALUE 273.16 K

The key comparison reference value, x_R, and its combined uncertainty, u_R, are calculated using the adaptive weighted average (DerSimonian-Laird procedure, see [1]) of the NIST Decision Tree [2]. For the particular data set of this key comparison, the result of the adaptive weighted average is identical to that of the conventional weighted average.

x_R = 4.7 µK

u_R = 7.2 µK

[1] R. DerSimonian, N. Laird (1986) "Meta-analysis in clinical trials," Controlled Clinical Trials 7(3):177-188.

[2] A. Possolo, A. Koepke, D. Newton, M.r. Winchester, "Decision Tree for Key Comparisons," 2021 J Res Natl Inst Stan 126:126007

The degree of equivalence of laboratory i with respect to the key comparison reference value is given by a pair of terms:
D_i = (x_i - x_R) and its expanded uncertainty U_i (k = 2), both expressed in µK.
The expanded uncertainties of the D_i take into account the correlations between the measured values and the key comparison reference value.

CCT-K7.2021

MEASURAND         Temperature of the triple point of water

NOMINAL VALUE       273.16 K

PILOT LABORATORY  NRC

x_i : temperature difference between the national reference of laboratory i and the pilot's reference, x_i = T_Labi - T_{Pilot Ref}, where T is the temperature

u_i : standard uncertainty of x_i 

See also section 5.1 of the Final report for the calculation of x_i and u_i