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National Technical University of Ukraine «Igor Sikorsky Kyiv Polytechnic Institute»
State enterprise "scientific and production center for standardization, metrology, certification and consumers rights protection"

The  article proposes  an  approach  to  the  research of  the metrological  reliability  of measurements  taking  into account the conditions and operating modes of measuring equipment, based on the intermediate control of the standard deviation of  the measurement  results.  The  above  approach  is  relevant  because  it  allows  laboratories  to  reasonably  set  the  recalibration intervals  of  measuring  equipment  based  on  the  control  of  standard  deviations.  The  requirement  for  reasonable  setting  of recalibration intervals for measuring instruments is a common worldwide practice.

A new concept of the critical sequence of points on the Shewhart control chart (s-chart) was introduced, the appearance of which indicates the presence of non-random variables of the measurement result by the measuring equipment. The probabilities of point sequences falling into certain ranges of the control chart are analyzed based on the law of distribution of standard deviation. It is proposed to subdivide the whole interval of probable hit of the standard deviation checkpoints on the Shewhart control chart for research purposes. Subsequently, a situation where a certain number of consecutive points falls within one or another range (or several adjacent ranges) was simulated, and it was proved that the occurrence of such critical points sequences on the control chart could indicate a loss of metrological reliability of the measuring instrument. To clarify the information, the article presents graphs of the probability of complex events (certain sequences of points) on the number of consecutive control points in the distribution ranges.

The  analysis made  it possible  to propose  the  criteria  for  establishing  the need  for  calibration or  repair of  the measuring equipment, based on the results of intermediate checks and control of the standard deviation.

[1]  ISO/IEC 17025:2017 General  requirements  for  the competence  of  testing  and  calibration  laboratories.  [Online]. Available:  https://www.iso.org/standard/66912.html. Accessed on: 2017.

[2]  ILAC-G 24/OIML D  10:2007  Guidelines  for  the determination  of  calibration  intervals  of  measuring  instruments.  [Online].  Available:  http://www.iec-ilac-iaf.org/doc/1007a.pdf. Accessed on:2007.

[3] ISO 5725-1:1994 Accuracy (trueness and precision) of  measurement  methods  and  results  –  Part  1:  General principles  and  definitions.  [Online].  Available: https://www.iso.org/standard/11833.html. Accessed on:1994.

[4] DSTU-N RMG 74:2009 Metrolohiia. Metody  vyznachennia mizhpovirkovoho  ta mizhkalibruvalnoho  intervaliv zasobiv  vymiriuvannia  (RMG  74-2004,  ІDT).  [Online]. Available:    http://online.budstandart.com/ua/catalog/doc-page?id_doc=62983. Accessed on: 2009.

[5]  E.  Volodarsky,  M.  Dobrolyubova,  M.  Klevtsova, “Sensitivity  analysis of Shewhart  control  charts”,  Information systems, mechanics and control, № 17, pp. 51–60, 2017.


[6]  ISO 7870-2:2013 Control charts – Part 2: Shewhart control  charts.  [Online].  Available: https://www.iso.org/standard/40174.html. Accessed on: 2013.

[7]  H.  Cramér,  Mathematical  methods  of  statistics, Princeton, NJ, US: Princeton University Press, 1999.