The Secondary Volume Laboratory (V0) of the National Metrology Center of Panama (CENAMEP AIP) has a validated calibration service for glass instruments based on the classical approach of the Guide for the Estimation of Measurement Uncertainty (GUM). However, the need of this study consisted in knowing the real nature of the influence quantities, analyzing the normality of the output quantity, to finally determine the ideal value of the coverage factor (k), for the operating conditions of the laboratory. The k factor allows estimation of the expanded uncertainty associated with the measurement result. The scope of this study comprises the analysis of the probability density function (PDF) assigned to the output quantity (V20), corresponding to the volume, from the Monte Carlo Method (MCM).

Data from calibrations of flasks, burettes and pipettes were used, by the gravimetric method in a measurement range from 1 mL to 1 000 mL. The MCM simulation was performed with the RStudio software tool. Normality was evaluated by graphical and statistical analysis by generating histograms and Q-Q Plot, and by calculating the kurtosis index and probability value by Lilliefors and Anderson-Darling tests, respectively. Based on the obtained results, it could be inferred that there are differences in the PDF behavior of the data set obtained for the different equipment tested in Panama.

It was concluded that V20 is not always normally distributed and that due to the use of the MCM more realistic results were obtained, which avoided making approximations and, therefore, represents an opportunity to improve the quality of the measurement process in this field of metrology. Therefore, this study allows the possibility of a revision of the existing regulations to examine the evaluation of uncertainty.