Concerning physical quantity, its true value, error, and measurement uncertainty

The former USSR journal «Ismeritelnaja technika» («Measurement technic») published the article by Vitalii Pronenko, one of the modern scientific metrology school creators, «Concerning physical quantity, its true value, measurement error, and uncertainty» («О физической величине, ее истинном значении, погрешности и неопределенности измерений»). As soon as the discussion concerning the review of the «International vocabulary of metrology — Basic and general concepts and associated terms», VIM-3, with the aim to create its new version VIM-4, runs now among the metrological community, our journal editorial team considers the article by Pronenko as actual taking in account its common philosophy content with consideration for modern concepts and associated terms. Due to war conditions in Ukraine, it is impossible to connect the editorial office of «Measurement technic» journal. So, the editorial team of «Measurements infrastructure» journal accepts its responsibility based on the agreement of Mr. Pronenko sons Serhii and Yurii Pronenko (Vitalii Pronenko passed away in 1990), the translation of the article by V. Pronenko, into Ukrainian and English and its publication on the journal site.

suggested to be considered as not necessary for the measurement technique and metrology because it is non-productive or it is impossible to be defined empirically precisely, and so on.It is considered [3] even as somehow application to God.Due to these or other reasons, it is suggested [2][3][4][5] to eliminate the concept of measurement error and replace it with the concept of measurement uncertainty.But in this case the enough clear definition of the uncertainty concept is not given.So, the basic concepts of measurement technique and metrology become debatable.But a prism is only a tool for cognition, not its subject.Such content of the physical quantity concept corresponds to the common opinion that measurement is the process of cognition and is in compliance with commonly known and approved in standard [1] term.

The proposition to review the definition of the
The suggested replacement of the physical quantity concept is unacceptable for theoretical metrology because it causes the replacement of the subject and aim of the measurement and also for the measurement technique and practical metrology because it In our opinion, the concept of measurement accuracy should correspond not to measurement error but measurement uncertainty, combined with the physical quantity true value uncertainty and the measurement error.So, for the example given above, even using the best instruments, there is no reason to speak about a rather precise measurement of the diameter for the shaft, the surface of which differs considerably from the surface of the round straight cylinder, if not to make the task more clear, for instance, by the condition that the adjoining from outside cylinder's diameter is to be measured.

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The random quantities displaying the physical quantity true value uncertainty and the measurement error are independent, that is why the uncertainty dispersion is equal to the sum of the physical quantity true value uncertainty dispersion and the dispersion of measurement error.
excludes a necessity of taking into accuracy characteristics account the reality inadequacy and its model.
The concept of the physical true value is associated with the reality model and its inadequacy degree -the concept of physical quantity true value uncertainty.The absence of the physical quantity true value concept among the widely used and fixed in standard [1] causes the non-completeness and incorrectness of «physical quantity true value» definition.
Nowadays, the true value is defined as such that displays ideally a property of the reality that corresponds to the physical quantity concept.But the word combination «displays ideally» is not revealed.
In our opinion, the parameter of the model, which corresponds to the physical quantity concept,  It is impossible to agree with the critics of physical quantity true value and the measurement error and considering them as non-productive and not needed [3][4][5] because it is impossible to define them precisely empirically.It was shown above their productivity and expedience.Besides that, it is useful to mention that most of the concepts of physics, other nature sciences, and mathematics (for example, gravity constant, electron charge, probability, the relation of circle length to its diameter, etc.) cannot be defined absolutely precisely empirically.

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But the question of their non-productivity and unnecessity had never been put.
The concept of a physical quantity, as the reality property that is the subject of cognition, true value, as the best physical quantity display while the reality model and their comparison criteria are accepted, the measurement error, as the characteristic of measurement results deviation from the physical quantity true value, and the measurements' uncertainty, as such concept that combines the uncertainty of true value with the measurements' error, and characterizes quantitively the quality of posterior imagine about the measurand.Accuracy characteristics, which are associated with measurement results, should be measurement uncertainty's characteristics.
The concept of measurement uncertainty is needed not to replace the concept of measurement error, as it is suggested in [4] , but to use together with the concept of measurement error as an independent term «physical quantity» and to consider the model parameter as the physical quantity should be considered as the proposition to review the subject of cognition, which is performed by measuring, to review the aim of measurement and the sense of result achieved by measuring.It is impossible to consider adequacy as the identity because the model is the product of thinking, approximate display of reality in mind, display of some of the most important its properties, their relationships, etc.No doubt, the measurement of physical quantity is impossible outside of the certain system of knowledge expressed with the model of reality.The imagination on the reality model's parameter should be obtained as the intermediate result, supplementing it with the imagination on reality model inadequacy.The measurement accuracy characteristics should be obtained by taking in account either the accuracy of reality model parameter evaluation or the accuracy with which the model displays the reality.Reality model is somehow a prism through which the reality, is a subject of cognition, is watched while measuring.

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Measurements infrastructure Vol.6 (2023) МІ_051_161023 Цитування виключно англомовної версії за https://doi.org/10.33955/v6(2023)-051www.mi-journal-online.org2021 Measurements infrastructure For instance, the real shaft is neither round nor straight.Usually, the measurement task's formulated in a very short way: to measure the shaft's diameter.From the task's formulation, it goes that the round straight cylinder shall be considered as the shaft model, to make the shaft's diameter certain.But the criteria for the comparison of the shaft with its model may be different: minimum of radial deviations of relevant surfaces' points sum (average diameter), the same, but under conditions that the deviations have the same sign (the diameter of the adjoining shaft -from outside or from inside), the minimum of deviations squared sum (the average square diameter), etc.If the measurement task is formulated completely certain and lays in, for instance, measuring the average diameter, the single true value exists, and its uncertainty is equal to zero.In the general case, in the measurement task formulation there exist several possible true values and the measurement result's interpretation is in practices random one.The expected value of these values is the true value and their dispersion -characteristic of the measurand's true value uncertainty.
the reality approximately and, in certain measurement tasks, accepts several interpretations and so is characterized by uncertainty.The true value should be considered as such a corresponding model parameter, that by it the model is maximum adequate to the reality and their inadequacy is at minimum.To define such optimum value means to solve the task with ambiguous (not completely defined) decision, because the criteria for inadequacy evaluation may be different.The true value may be considered as unambiguous one only in case when the measurement task is formulated so that the criteria for inadequacy evaluation is derived from the task formulation and causes availability of the choosing the single model parameter, to which model's inadequacy amounts are minimum.In general, the evaluation criteria are ambiguous in the task's formulation.The uncertainty (plurality) of the evaluation criteria causes the uncertainty of the physical quantity true value (plurality of the available true values).Those physical quantity values, to each of which corresponds one of the reasonable criteria, should be considered as possible true values for this physical quantity.They should be considered as the realizations of certain random quantity, the expected value of which is the true value of physical quantity and the dispersion and other characteristics -the characteristics of its true value uncertainty.