## 4 Conclusions  
With regard to the uncertainty of the assigned values and after considering the modifications applied to the estimation of their uncertainty using the thermistor cryoscope method, it is concluded that the criterion established in the ISO 13528:2022 standard is not met. Therefore, it is recommended to take this into account for future rounds, as it will imply the evaluation of the participants' performance based on z\({}^{\prime}\)-score. The participants should be informed that the risk of an erroneous evaluation of the performance is slightly increased. This higher risk would only affect borderline cases ( \(\mid\) z\({}^{\prime}\)-score \(\mid\) close to 2.0 or 3.0) and in the present research would correspond to 2.9% of the total number of participations. On the other hand, with respect to the MIR mid-infrared spectroscopy method, the criterion for uncertainty is met in 55.6% of the rounds. However, it must be noted that participants using the MIR method corresponded to 5.6% of the total number of laboratories. \begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**PT Code**} & \multirow{2}{*}{**PT Item**} & **Reference** & **Consensus** & **Difference m\({}^{\circ}\)C** \\  & & **Value** & **Value** & **(Consensus–** \\  & & **m\({}^{\circ}\)C** & **m\({}^{\circ}\)C** & **Reference)** \\ \hline \multirow{3}{*}{PC LC 1701} & 01 & \(-\)521.2 & \(-\)523.2 & \(-\)2.0 \\  & 02 & \(-\)529.8 & \(-\)531.4 & \(-\)1.6 \\  & 03 & \(-\)498.3 & \(-\)500.9 & \(-\)2.6 \\ \hline \multirow{3}{*}{PC LC 1702} & 01 & \(-\)502.8 & \(-\)507.6 & \(-\)4.8 \\  & 02 & \(-\)519.3 & \(-\)522.4 & \(-\)3.1 \\  & 03 & \(-\)519.0 & \(-\)524.5 & \(-\)5.5 \\ \hline \multirow{3}{*}{PC LC 1801} & 01 & \(-\)524.2 & \(-\)526.4 & \(-\)2.2 \\  & 02 & \(-\)530.0 & \(-\)533.3 & \(-\)3.3 \\  & 03 & \(-\)515.8 & \(-\)517.2 & \(-\)1.4 \\ \hline \multirow{3}{*}{PC LC 1802} & 01 & \(-\)521.2 & \(-\)522.5 & \(-\)1.3 \\  & 02 & \(-\)521.0 & \(-\)523.3 & \(-\)2.3 \\  & 03 & \(-\)506.5 & \(-\)507.7 & \(-\)1.2 \\  & 01 & \(-\)504.8 & \(-\)508.2 & \(-\)3.4 \\ \cline{1-1}  & 02 & \(-\)511.5 & \(-\)514.4 & \(-\)2.9 \\ \cline{1-1}  & 03 & \(-\)521.0 & \(-\)522.6 & \(-\)1.6 \\ \hline \multirow{3}{*}{PC LC 1902} & 01 & \(-\)521.7 & \(-\)524.1 & \(-\)2.4 \\ \cline{1-1}  & 02 & \(-\)521.0 & \(-\)523.6 & \(-\)2.6 \\ \cline{1-1}  & 03 & \(-\)506.8 & \(-\)508.1 & \(-\)1.3 \\ \hline \multirow{3}{*}{PC LC 2001} & 01 & \(-\)530.7 & \(-\)534.3 & \(-\)3.6 \\ \cline{1-1}  & 02 & \(-\)524.8 & \(-\)528.2 & \(-\)3.4 \\ \cline{1-1}  & 03 & \(-\)513.8 & \(-\)517.2 & \(-\)3.4 \\ \hline \multirow{3}{*}{PC LC 2002} & 01 & \(-\)518.8 & \(-\)520.6 & \(-\)1.8 \\ \cline{1-1}  & 02 & \(-\)521.8 & \(-\)522.6 & \(-\)0.8 \\ \cline{1-1}  & 03 & \(-\)509.0 & \(-\)511.6 & \(-\)2.6 \\ \hline \multirow{3}{*}{PC LC 2101} & 01 & \(-\)512.0 & \(-\)513.1 & \(-\)1.1 \\ \cline{1-1}  & 02 & \(-\)515.3 & \(-\)517.7 & \(-\)2.4 \\ \cline{1-1}  & 03 & \(-\)520.5 & \(-\)522.4 & \(-\)1.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Summary table of the reference values assigned by calibration assay and robust consensus mean of the participants’ results obtained through the thermistor cryoscope method. With respect to the criteria for performance evaluation, in 92.6% of the tested PT items, the laboratories that applied the thermistor cryoscope method were able to achieve a robust standard deviation below the value of \(\vartheta\), which shows that, in general, the laboratories are able to operate under the precision indexes established for the analytical method and that it is feasible to continue using a value of \(\vartheta\) equal to 3 m\({}^{\circ}\)C. Moreover, it should be noted that the precision indexes for this analytical method have not been modified in the ISO 5764:2009 standard. For the MIR method, it is recommended to maintain the standard deviation for the evaluation of the estimated proficiency based on the manufacturer's precision data.