Verso il VIM4? La situazione delle attività del JCGM / WG2 (VIM) Luca Mari.

Transcription

1 Verso il VIM4? La situazione delle attività del JCGM / WG2 (VIM) Luca Mari lmari@liuc.it XXXIII Giornata della Misurazione, Roma 2014

2 Trent anni dopo...

3 The context: JCGM and its products Metrology: a moving target Towards the VIM4

4 Joint Committee for Guides in Metrology (JCGM) (established in 1997) (BIPM) Int.l Bureau of Weights and Measures (IEC) Int.l Electrotechnical Commission (IFCC) Int.l Federation of Clinical Chemistry and Laboratory Medicine (ILAC) Int.l Laboratory Accreditation Cooperation (ISO) Int.l Organization for Standardization (IUPAC) Int.l Union of Pure and Applied Chemistry (IUPAP) Int.l Union of Pure and Applied Physics (OIML) Int.l Organization of Legal Metrology

5 The scope of JCGM metrology: : «science of measurement and its application» no principled constraints on the object of measurement...

6 JCGM guidance documents VIM GUM vim.html gum.html

7 The VIM...

8 ... is only a vocabulary but let us compare it, e.g., with Electropedia

9 Searching Electropedia for sensitivity :

10 The hypothesis underlying the JCGM (including IEC...) endeavor is that today: the basic concepts of metrology can be consistently and univocally defined such a system of definitions is useful for many classes of readers «This Vocabulary is meant to be a common reference for scientists and engineers including physicists, chemists, medical scientists as well as for both teachers and practitioners involved in planning or performing measurements, irrespective of the level of measurement uncertainty and irrespective of the field of application. It is also meant to be a reference for governmental and inter- governmental bodies, trade associations, accreditation bodies, regulators, and professional societies.» [VIM3: Scope]

11 VIM1 International vocabulary of basic and general terms in metrology 1984 (with corrections: 1987) ISO: standardization IEC: standardization BIPM: fundamental metrology OIML: legal metrology VIM1 1984

12 VIM2 International vocabulary of basic and general terms in metrology 1993 [ISO Guide 99:1993] ISO: standardization IEC: standardization VIM BIPM: fundamental metrology VIM ISO/TAG 4 OIML: legal metrology IUPAP: physics IUPAC: chemistry IFCC: clinical chemistry laboratory medicine

13 VIM3 International vocabulary of metrology Basic and general concepts and associated terms 2007 (with corrections: 2012) [JCGM 200:2012] ISO: standardization IEC: standardization VIM ILAC: accreditation BIPM: fundamental metrology VIM JCGM OIML: legal metrology IFCC: clinical chemistry laboratory medicine VIM3 IUPAC: chemistry 2007 IUPAP: physics

14 The VIM3+A (?)

15 The VIMs as witnesses of change The VIMs can be considered as conceptual and lexical snapshots, taken from a conservative viewpoint (the existing widespread metrological infrastructure, standards, accreditation procedures, have to be maintained) from a political viewpoint (changes require the consensus of all Member Organizations) and nevertheless some interesting changes can be found from the VIM1, mainly reflecting the traditional standpoint to the VIM3 and now towards the VIM4

16 The context: JCGM and its products Metrology: a moving target What is measurable? What is measured? What is measurement? Towards the VIM4

17 From the VIM1 to the VIM3: some fundamental changes What is measurable? The traditional position: Measurability is a feature of empirical properties that can be compared with each other in terms of their ratio

18 Properties and quantities The VIM1 adopts the traditional position and presents it in reference to quantities,, by assuming that: 1. quantities are specific properties 2. only quantities are measurable property VIM1 measurable property = quantity The status of ordinal properties remains (undefined and) ambiguous here...

19 Properties and quantities again The VIM3 maintains the VIM1 assumptions, but defines ordinal properties as ordinal quantities An ordinal quantity is a «quantity, defined by a conventional measurement procedure, for which a total ordering relation can be established, according to magnitude, with other quantities of the same kind, but for which no algebraic operations among those quantities exist» property VIM3 nominal property measurable property = quantity ordinal quantity quantity expressed by a measurement unit

20 From the VIM1 to the VIM3: some fundamental changes What is measured? The traditional position: Measurement conveys uninterpreted information on the empirical property in input to the measuring instrument

21 Measurands The VIM1 adopts the traditional position and presents it in reference to measurands,, by assuming that: 1. measurement is a «set of operations having the object of determining the value» of a measurand 2. a measurand is a «quantity subjected to measurement» VIM1 object under measurement measurand measuring system measurement result

22 Measurands again The VIM3 redefines measurand as a «quantity intended to be measured» object under measurement VIM3 quantity subject to measurement experimental component model-based component measurement result attributed to measurand The idea: we do our best to let the measuring system interact with the quantity we want to measure, but the measurement result will be attributed to the quantity as we have defined it, not to the (unknown) quantity with which the instrument actually interacted

23 From the VIM1 to the VIM3: some fundamental changes What is measurement? The traditional position: Measurement is a purely experimental process

24 Measurement The VIM1 adopts the traditional position and presents it in reference to measurement,, by assuming that: 1. it is a determination process whose outcome preexists to measurement itself 2. the measurand has a single value VIM1 Measurement is aimed at «determining the value of a quantity»

25 Measurement again The VIM3 redefines measurement as a «process of experimentally obtaining one or more quantity values that can reasonably be attributed to a quantity» VIM3 How can this reasonable attribution be obtained?

26 The context: JCGM and its products Metrology: a moving target Towards the VIM4

27 Towards the VIM4 The current edition of the VIM is still a half refined document: the JCGM is expecting a first public draft of the next edition by 2018 At the moment the only formal requirement of the JCGM is to better integrate nominal properties and the related concepts

28 E il momento giusto per proporre soluzioni per alcuni problemi di base...

29 1. In vista del VIM4 la composizione del JCGM potrebbe / dovrebbe essere utilmente estesa ad altre organizzazioni? 2. I concetti di base della metrologia possono davvero essere definiti in modo consistente e univoco? 3. Ha senso trattare in uno stesso documento concetti relativi a proprietà classificatorie e grandezze, e come farlo? 4. Per quali utenti è scritto il VIM, e quindi in particolare quali precompetenze si può ipotizzare che abbia il suo utente tipo? 5. Il VIM4 dovrebbe rimanere un vocabolario, o dovrebbe diventare un ontologia? Dovrebbe includere una narrazione? 6. Data la composizione del JCGM, la componente accademica è quasi del tutto ininfluente nello sviluppo del VIM: ha invece senso che riesca a dare il suo contributo, e come?

30 THANK YOU FOR YOUR KIND ATTENTION Luca Mari