Can there be a metrology for...

Can there be a metrologyCan there be a metrologyfor psychometricians?for psychometricians?

Luca MariLuca MariUniversità Cattaneo – LIUC, ItalyUniversità Cattaneo – LIUC, Italy

BEAR Seminar, University of California, BerkeleyBEAR Seminar, University of California, BerkeleyTuesday, January 31, 2017Tuesday, January 31, 2017

AbstractAbstract

Metrology -- the “science of measurement and its application” according to Metrology -- the “science of measurement and its application” according to the the International Vocabulary of MetrologyInternational Vocabulary of Metrology (VIM) -- is a body of knowledge (VIM) -- is a body of knowledge traditionally bound to the measurement of physical quantities, sometimes traditionally bound to the measurement of physical quantities, sometimes with the further specification that only high quality (in some sense to be with the further specification that only high quality (in some sense to be agreed) measurement-related activities constitute actual metrology, as agreed) measurement-related activities constitute actual metrology, as those performed in the US by the NIST.those performed in the US by the NIST.

Given the social reputation of measurement, it is not amazing that there is a Given the social reputation of measurement, it is not amazing that there is a tension to continue the historical process of expanding such a still strict tension to continue the historical process of expanding such a still strict scope, where in particular under scrutiny is the necessity that the object of scope, where in particular under scrutiny is the necessity that the object of measurement is a physical quantity.measurement is a physical quantity.

Arguing about metrology is then a good opportunity to discuss of the very Arguing about metrology is then a good opportunity to discuss of the very nature of measurement and its limits, between science, technology, nature of measurement and its limits, between science, technology, mathematics, and society.mathematics, and society.

Luca Mari (MS in physics, University of Milano, Italy, 1987; Ph.D. in Luca Mari (MS in physics, University of Milano, Italy, 1987; Ph.D. in measurement science, Polytechnic of Torino, Italy, 1994) since 2006 measurement science, Polytechnic of Torino, Italy, 1994) since 2006 has been a full professor of measurement science with Università has been a full professor of measurement science with Università Cattaneo - LIUC, Castellanza, Italy, where he teaches courses on Cattaneo - LIUC, Castellanza, Italy, where he teaches courses on measurement science, statistical data analysis, and system theory.measurement science, statistical data analysis, and system theory.

He is currently the chairman of the TC1 (Terminology) and the secretary He is currently the chairman of the TC1 (Terminology) and the secretary of the TC25 (Quantities and units) of the International Electrotechnical of the TC25 (Quantities and units) of the International Electrotechnical Commission (IEC), and an IEC expert in the WG2 (VIM) of the Joint Commission (IEC), and an IEC expert in the WG2 (VIM) of the Joint Committee for Guides in Metrology (JCGM). He has been the chairman Committee for Guides in Metrology (JCGM). He has been the chairman of the TC7 (Measurement Science) of the International Measurement of the TC7 (Measurement Science) of the International Measurement Confederation (IMEKO).Confederation (IMEKO).

My profileMy profile

LM, P.Blattner, F.Pavese, LM, P.Blattner, F.Pavese, Improving the understandability of the next edition of the International System Improving the understandability of the next edition of the International System of Units (SI) by focusing on its conceptual structureof Units (SI) by focusing on its conceptual structure , , MeasurementMeasurement, 2017 , 2017

LM, A.Maul, D.Torres Irribarra, M.Wilson, LM, A.Maul, D.Torres Irribarra, M.Wilson, Quantities, quantification, and the necessary and sufficient Quantities, quantification, and the necessary and sufficient conditions for measurementconditions for measurement, , MeasurementMeasurement, 2017, 2017

D.Petri, LM, P.Carbone, D.Petri, LM, P.Carbone, A structured methodology for measurement developmentA structured methodology for measurement development, , IEEE Trans. Instr. IEEE Trans. Instr. Meas.Meas., 2015, 2015

A.Mencattini, LM, A.Mencattini, LM, A conceptual framework for concept definition in measurement: the case of A conceptual framework for concept definition in measurement: the case of 'sensitivity''sensitivity', , MeasurementMeasurement, 2015, 2015

LM, LM, Evolution of 30 years of the International Vocabulary of Metrology (VIM)Evolution of 30 years of the International Vocabulary of Metrology (VIM) , , MetrologiaMetrologia, 2015, 2015

LM, D.Petri, LM, D.Petri, Measurement science: constructing bridges between reality and knowledgeMeasurement science: constructing bridges between reality and knowledge , , IEEE Inst. IEEE Inst. Meas. Mag.Meas. Mag., 2014, 2014

P.Micheli, LM, P.Micheli, LM, The theory and practice of performance measurementThe theory and practice of performance measurement , , Management Accounting ResearchManagement Accounting Research, , 20142014

LM, M.Wilson, LM, M.Wilson, An introduction to the Rasch measurement approach for metrologistsAn introduction to the Rasch measurement approach for metrologists , , MeasurementMeasurement, , 20142014

A.Frigerio, A.Giordani, LM, A.Frigerio, A.Giordani, LM, On representing information: a characterization of the analog/digital On representing information: a characterization of the analog/digital distinctiondistinction, , DialecticaDialectica, 2013, 2013

LM, LM, A quest for the definition of measurementA quest for the definition of measurement, , MeasurementMeasurement, 2013, 2013

LM, A.Giordani, LM, A.Giordani, Quantity and quantity valueQuantity and quantity value, , MetrologiaMetrologia, 2012, 2012

LM, P.Carbone, D.Petri, LM, P.Carbone, D.Petri, Measurement fundamentals: a pragmatic viewMeasurement fundamentals: a pragmatic view, , IEEE Trans. Instr. Meas.IEEE Trans. Instr. Meas., 2012, 2012

A.Giordani, LM, A.Giordani, LM, Measurement, models, uncertaintyMeasurement, models, uncertainty, , IEEE Trans. Instr. Meas.IEEE Trans. Instr. Meas., 2012, 2012

A.Giordani, LM, A.Giordani, LM, Property evaluation typesProperty evaluation types, , MeasurementMeasurement, 2012, 2012

Some of my recent publicationsSome of my recent publications

The (meta-)message: metrology is less monolithicThe (meta-)message: metrology is less monolithicthan possibly supposed “from the outside”than possibly supposed “from the outside”

Taking a look at the ways it is differently interpretedTaking a look at the ways it is differently interpretedmay suggest some hypotheses on howmay suggest some hypotheses on howthe sciences of physical and non-physical measurementthe sciences of physical and non-physical measurementcould learn from each othercould learn from each other

The proposal:The proposal:

a short discussion on four interpretationsa short discussion on four interpretationsof what metrology is,of what metrology is,

each from a strict, traditional standpointeach from a strict, traditional standpointtoward a broader, encompassing viewtoward a broader, encompassing view

… … with a premise,with a premise,

aimed at providing a context for the discussionaimed at providing a context for the discussion

and hopefully at sharing some basic concepts and termsand hopefully at sharing some basic concepts and terms

Joint CommitteeJoint Committeefor Guides in Metrologyfor Guides in Metrology(JCGM)(JCGM)

BIPMBIPM Int.l Bureau of Weights and MeasuresInt.l Bureau of Weights and Measures

OIMLOIML Int.l Organization of Legal MetrologyInt.l Organization of Legal Metrology

ISOISO Int.l Organization for StandardizationInt.l Organization for Standardization

IECIEC Int.l Electrotechnical CommissionInt.l Electrotechnical Commission

ILACILAC Int.l Laboratory Accreditation CooperationInt.l Laboratory Accreditation Cooperation

IUPAPIUPAP Int.l Union of Pure and Applied PhysicsInt.l Union of Pure and Applied Physics

IUPACIUPAC Int.l Union of Pure and Applied ChemistryInt.l Union of Pure and Applied Chemistry

IFCCIFCC Int.l Federation of Clinical Chemistry and Lab. MedicineInt.l Federation of Clinical Chemistry and Lab. Medicine

(established in 1997)

Joint CommitteeJoint Committeefor Guides in Metrologyfor Guides in Metrology(JCGM)(JCGM)

MetrologyMetrology : : BIPMBIPM

Legal metrologyLegal metrology : OIML : OIML

StandardizationStandardization : ISO : ISO IECIEC

AccreditationAccreditation : ILAC : ILAC

Domain-related Domain-related : : IUPAP (physics) IUPAC (chemistry)IUPAP (physics) IUPAC (chemistry)IFCC (clinical chemistry and lab medicine)IFCC (clinical chemistry and lab medicine)

(established in 1997)

http://www.bipm.org/en/publications/guides/

vim.htmlgum.html

the VIM the GUM

JCGM “guidance docs”JCGM “guidance docs”

The scope of JCGMThe scope of JCGM

metrologymetrology: «science of measurement and its application» : «science of measurement and its application» [VIM, def. 2.2][VIM, def. 2.2]

«In this Vocabulary [the VIM], it is taken for granted that«In this Vocabulary [the VIM], it is taken for granted thatthere is no fundamental difference in the basic principles of measurementthere is no fundamental difference in the basic principles of measurementin physics, chemistry, laboratory medicine, biology, or engineering.in physics, chemistry, laboratory medicine, biology, or engineering.Furthermore, an attempt has been madeFurthermore, an attempt has been madeto meet conceptual needs of measurement in fields such asto meet conceptual needs of measurement in fields such asbiochemistry, food science, forensic science, and molecular biology.»biochemistry, food science, forensic science, and molecular biology.»

A terminological premiseA terminological premise

According to the VIMAccording to the VIM::

measurementmeasurement: the process of measuring: the process of measuring

measurandmeasurand: the quantity intended to be measured: the quantity intended to be measured

measurement resultmeasurement result: the outcome of measurement,: the outcome of measurement,in the form of a in the form of a quantity valuequantity value

(or an interval of quantity values, a pdf on a set of quantity values, etc)(or an interval of quantity values, a pdf on a set of quantity values, etc)

(the VIM avoids the noun “measure” because too ambiguous)(the VIM avoids the noun “measure” because too ambiguous)

A conceptual premiseA conceptual premise

quantitiesquantities are arespecific specific propertiesproperties::

{quantities} {quantities} {properties} {properties}

properties

quantities

measurementsmeasurements are arespecific specific evaluationsevaluations::

{measurements} {measurements} {evaluations} {evaluations}

evaluations

measurements

Why could the question “Why could the question “what is metrology?what is metrology?” ” be interesting to psychometricians?be interesting to psychometricians?

1. Metrology is a socially acknowledged context of measurement1. Metrology is a socially acknowledged context of measurement

2. T2. The public trust attributed to measurement resultshe public trust attributed to measurement resultsis not attributed to the outcomes of other forms of evaluationis not attributed to the outcomes of other forms of evaluation

Hence claims such as “this information comes from a measurement”,Hence claims such as “this information comes from a measurement”,and “this information is provided by a metrological institution”,and “this information is provided by a metrological institution”,have a societal significancehave a societal significance

((and in a situation of post-truth and alternative facts...and in a situation of post-truth and alternative facts...))

Four interpretations:Four interpretations:

metrology is...metrology is...

1. the body of knowledge1. the body of knowledgeabout evaluations of physical propertiesabout evaluations of physical properties

2. 2. the body of knowledge about measuresthe body of knowledge about measures

3. 3. what National Metrology Institutes dowhat National Metrology Institutes do

4. the body of knowledge4. the body of knowledgeabout evaluations of sufficiently high qualityabout evaluations of sufficiently high quality

These interpretations are not alternative…These interpretations are not alternative…

… … and in fact a (very conservative) position might consider metrology asand in fact a (very conservative) position might consider metrology aswhat National Metrology Institutes do relating to sufficiently high quality what National Metrology Institutes do relating to sufficiently high quality evaluations of physical quantitiesevaluations of physical quantities

More explicitly:More explicitly:«Metrology is the science of measurement. It covers three main activities:«Metrology is the science of measurement. It covers three main activities:1. the definition of internationally accepted units of measurement, e.g. the metre;1. the definition of internationally accepted units of measurement, e.g. the metre;2. the realization of units of measurement by scientific methods,2. the realization of units of measurement by scientific methods,

e.g. the realization of a metre through the use of lasers;e.g. the realization of a metre through the use of lasers;3. the establishment of traceability chains by determining and documenting3. the establishment of traceability chains by determining and documenting

the value and accuracy of a measurement and disseminating that knowledge, the value and accuracy of a measurement and disseminating that knowledge, e.g. the documented relationship between the micrometer screw in a precisione.g. the documented relationship between the micrometer screw in a precisionengineering workshop and a primary laboratory for optical length metrology.»engineering workshop and a primary laboratory for optical length metrology.»

[Metrology in short, 3rd edition, EURAMET project 1011, 2008, [Metrology in short, 3rd edition, EURAMET project 1011, 2008, http://www.euramet.org/publications-media-centre/documents/metrology-in-short]http://www.euramet.org/publications-media-centre/documents/metrology-in-short]

A mini-tutorial on metrology...A mini-tutorial on metrology...

quantitiesquantities objectsobjects

1. an individual quantity is defined1. an individual quantity is defined(kilogram, i.e., the mass of the object…):(kilogram, i.e., the mass of the object…):

quantity unitquantity unit

for each general quantity for each general quantity (e.g., mass)(e.g., mass)

2. the unit is realized into an object2. the unit is realized into an object(IPK, the Int.l Prototype of the Kilogram):(IPK, the Int.l Prototype of the Kilogram):

primary measurement standardprimary measurement standard

(simplified version)(simplified version)

3. other compatible standards3. other compatible standardsare realized and disseminated:are realized and disseminated:

national / working standardsnational / working standards

3’. measuring instruments3’. measuring instrumentsare calibrated againstare calibrated against

working standardsworking standards4. 4. measurement resultsmeasurement results

realizationrealization

disseminationdissemination

calibrationcalibration

measurementmeasurement

traceability of traceability of measurement results measurement results

to the unitto the unit

((such a strict standpointsuch a strict standpointis plausibly not so interestingis plausibly not so interesting

to psychometricians...to psychometricians...))

““Strict” metrologyStrict” metrology

is aboutis about

with high qualitywith high qualityinstrumentsinstrumentsand resultsand results

quantitiesquantities

evaluatedevaluatedintersubjectivelyintersubjectivelyvia universal unitsvia universal units

physicalphysical

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physicalphysical

““Broad” metrologyBroad” metrology

could be aboutcould be about

?? ??

????

Interpretation 1 (Interpretation 1 (disciplinarydisciplinary characterization) characterization)

metrology is the body of knowledgemetrology is the body of knowledgeabout evaluations of about evaluations of physicalphysical properties properties

RationaleRationale::measurement historically developedmeasurement historically developedrelating to geometrical quantitiesrelating to geometrical quantities

Broadening interpretation 1...Broadening interpretation 1...

The concept ‘measurable property’ has widened its scope in historyThe concept ‘measurable property’ has widened its scope in history(the term “weights and measures” is the trace of a not so far past(the term “weights and measures” is the trace of a not so far pastin which weights were not considered measures...)in which weights were not considered measures...)

Q: can non-physical properties be measured?Q: can non-physical properties be measured?

physicalphysicalpropertiesproperties

not only physicalnot only physicalpropertiesproperties

Interpretation 2 (Interpretation 2 (semanticsemantic characterization) characterization)

metrology is the body of knowledge about metrology is the body of knowledge about quantitiesquantities,,i.e., “measures”i.e., “measures”

RationaleRationale::‘measurement’ and ‘measure’ belong to‘measurement’ and ‘measure’ belong tothe same concept system the same concept system


Despite they seem to be coextensive,Despite they seem to be coextensive,the concepts ‘measurement’ and ‘measure’ are different,the concepts ‘measurement’ and ‘measure’ are different,and measure theory is a mathematical theory about additive properties and measure theory is a mathematical theory about additive properties (i.e., Euclidean quantities and their generalizations)(i.e., Euclidean quantities and their generalizations)

Q: can non-Euclidean / non-additive / non-ratio properties be measured?Q: can non-Euclidean / non-additive / non-ratio properties be measured?

quantitiesquantities not only additive not only additive propertiesproperties

Interpretation 3 (Interpretation 3 (organizationalorganizational characterization) characterization)

metrology is what National Metrology Institutes (NMIs) dometrology is what National Metrology Institutes (NMIs) doto guarantee to guarantee intersubjectivity of evaluationsintersubjectivity of evaluationsvia universal unitsvia universal units

RationaleRationale::NMI activity is the foundation of the metrological systemNMI activity is the foundation of the metrological system


NMIs develop and disseminate measurement standardsNMIs develop and disseminate measurement standardsas tools for making intersubjectivity in measurement possibleas tools for making intersubjectivity in measurement possible

Q: can intersubjectivity of information on empirical propertiesQ: can intersubjectivity of information on empirical propertiesbe guaranteed without universal units?be guaranteed without universal units?

intersubjectivityintersubjectivityby universal unitsby universal units

intersubjectivityintersubjectivityby some general strategiesby some general strategies

Interpretation 4 (Interpretation 4 (axiologicalaxiological characterization) characterization)

metrology is the body of knowledgemetrology is the body of knowledgeabout evaluations of about evaluations of sufficiently high qualitysufficiently high quality

RationaleRationale::measurement is widespreadmeasurement is widespreadand not any measurement is a metrological activityand not any measurement is a metrological activity


Metrology is sometimes intended (particularly by NMIs) as only covering Metrology is sometimes intended (particularly by NMIs) as only covering “scientific” measurement, with “small” measurement uncertainty“scientific” measurement, with “small” measurement uncertainty

What is important here is that measurement results convey informationWhat is important here is that measurement results convey informationas both quantity / property values and quality of such valuesas both quantity / property values and quality of such values

evaluationsevaluationsof high qualityof high quality

evaluationsevaluationsof stated qualityof stated quality

SynthesisSynthesis




physicalphysical

From “strict” to “broad” metrologyFrom “strict” to “broad” metrology

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physicalphysical

““Broad” metrologyBroad” metrology

could be aboutcould be aboutnot only physicalnot only physicalpropertiesproperties

not only additive not only additive propertiesproperties

evaluated intersubjectivelyevaluated intersubjectivelyvia some general strategiesvia some general strategies

with quality statedwith quality statedaccording to well defined proceduresaccording to well defined procedures

((such a “broad” metrology seems to be a contextsuch a “broad” metrology seems to be a contextwhere psychometricians and engineerswhere psychometricians and engineers

can productively work together...can productively work together...))

THANK YOUTHANK YOUFOR YOUR KIND ATTENTIONFOR YOUR KIND ATTENTION

Luca MariLuca [email protected] [email protected]

http://research.liuc.it/luca.marihttp://research.liuc.it/luca.mari

Can there be a metrologyCan there be a metrologyfor psychometricians?for psychometricians?

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