education 274c: research seminar in measurement...

Education 274C: Research Seminar in Measurement:Education 274C: Research Seminar in Measurement:

Philosophy of MeasurementPhilosophy of Measurement

2. Metrology2. Metrology

Luca MariLuca [email protected]@liuc.it

research.liuc.it/luca.mariresearch.liuc.it/luca.mari

January 23, 2018January 23, 2018

[M.Sc. in physics; Ph.D. in measurement science][M.Sc. in physics; Ph.D. in measurement science]

I am full professor of measurement science at the Cattaneo University – I am full professor of measurement science at the Cattaneo University – LIUC, Castellanza (VA), Italy, where I teache courses on measurement LIUC, Castellanza (VA), Italy, where I teache courses on measurement science, statistical data analysis, system theory.science, statistical data analysis, system theory.

I am currently the chairman of the TC1 (Terminology) and the secretary of I am currently the chairman of the TC1 (Terminology) and the secretary of the TC25 (Quantities and Units) of the International Electrotechnical 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). I have been the chairman of Committee for Guides in Metrology (JCGM). I have been the chairman of the TC7 (Measurement Science) of the International Measurement the TC7 (Measurement Science) of the International Measurement Confederation (IMEKO).Confederation (IMEKO).

I am the author or coauthor of several scientific papers published in I am the author or coauthor of several scientific papers published in international journals and international conference proceedings. My international journals and international conference proceedings. My research interests include measurement science and system theory.research interests include measurement science and system theory.

You can reach me at You can reach me at [email protected]@liuc.it

My profileMy profile

LM, P.Carbone, A.Giordani, D.Petri, LM, P.Carbone, A.Giordani, D.Petri, A structural interpretation of measurement and some related A structural interpretation of measurement and some related epistemological issuesepistemological issues, , Studies in History and Philosophy of ScienceStudies in History and Philosophy of Science, 2017, 2017

LM, LM, Toward a harmonized treatment of nominal properties in metrologyToward a harmonized treatment of nominal properties in metrology, , MetrologiaMetrologia, 2017, 2017

LM, D.Petri, LM, D.Petri, The metrological culture in the context of Big Data: Managing data-driven decision The metrological culture in the context of Big Data: Managing data-driven decision confidenceconfidence, , IEEE Instrumentation and Measurement Mag.IEEE Instrumentation and Measurement Mag., 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

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

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. Instrumentation IEEE Trans. Instrumentation and Measurementand Measurement, 2012, 2012

A.Giordani, LM, A.Giordani, LM, Measurement, models, uncertaintyMeasurement, models, uncertainty, , IEEE Trans. Instrumentation and MeasurementIEEE Trans. Instrumentation and Measurement, , 20122012

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

A.Frigerio, A.Giordani, LM, A.Frigerio, A.Giordani, LM, Outline of a general model of measurementOutline of a general model of measurement, , SyntheseSynthese, 2010, 2010

LM, LM, The problem of foundations of measurementThe problem of foundations of measurement, , MeasurementMeasurement, 2005, 2005

LM, LM, Epistemology of measurementEpistemology of measurement, , MeasurementMeasurement, 2003, 2003

Some of my Some of my (more philosophically oriented)(more philosophically oriented) publications publications

from the Course Overviewfrom the Course Overview

This course [...] will provide a general introduction to the This course [...] will provide a general introduction to the philosophical foundations of measurement theory, with a philosophical foundations of measurement theory, with a special focus on measurement in the social sciences.special focus on measurement in the social sciences.

[...] [...] we will explore the relationship between we will explore the relationship between psychometrics and metrologypsychometrics and metrology (i.e., the science of (i.e., the science of measurement, classically meaning physical measurement, classically meaning physical measurement).measurement).

Q1: What is the result of 1 + 10Q1: What is the result of 1 + 10–9–9 ? ?

One problem, three problemsOne problem, three problems

A1: 1.000000001A1: 1.000000001

Q2: What is the length of the segment Q2: What is the length of the segment aa++bb where: where:

len(len(aa) = 1 m) = 1 m len(len(bb) = 1 nm) = 1 nm

A2: len(A2: len(aa++bb) = 1.000000001 m) = 1.000000001 m

Q3: What is the length of the physical object Q3: What is the length of the physical object aa++bb where: where:

len(len(aa) = 1 m) = 1 m len(len(bb) = 1 nm) = 1 nm

Three problems, three solutionsThree problems, three solutions

Q2: What is the length of the segment Q2: What is the length of the segment aa++bb, len(, len(aa)=1 m, len()=1 m, len(bb)=1 nm ?)=1 nm ?

→ → A A geometricgeometric problem, solved by computation with units problem, solved by computation with units

A3 (plausibly): len(A3 (plausibly): len(aa++bb) = 1 m) = 1 m

Q1: What is the result of 1 + 10Q1: What is the result of 1 + 10–9–9 ? ?

→ → An An algebraicalgebraic problem, solved by computation problem, solved by computation

Q3: What is the length of the physical object Q3: What is the length of the physical object aa++bb, len(, len(aa)=1 m, len()=1 m, len(bb)=1 nm ?)=1 nm ?

→ → A A measurementmeasurement problem problem

Measurement problems: the set upMeasurement problems: the set up

We acknowledge that in the empirical world there are:We acknowledge that in the empirical world there are:

* * objectsobjects (phenomena, processes, events, ...) (phenomena, processes, events, ...)

* having * having propertiesproperties (attributes, features, ...) (attributes, features, ...)

* by which objects can be * by which objects can be comparedcompared,,and sometimes prove to be indistinguishableand sometimes prove to be indistinguishable

By some of their properties objects can also be By some of their properties objects can also be orderedordered

By some of their properties objects can also be By some of their properties objects can also be composed additivelycomposed additively

Metrology grew up from additive propertiesMetrology grew up from additive properties

An example (cont.d)An example (cont.d)

Synthesis:Synthesis:

in measurement we exploit modelsin measurement we exploit models(e.g., this physical object is a cylinder and as such has a length)(e.g., this physical object is a cylinder and as such has a length)

and we should remember that what we reportand we should remember that what we report

as measurement resultsas measurement results

is related to the empirical world through modelsis related to the empirical world through models

object undermeasurement

Measurement as a black boxMeasurement as a black box

property subjectto measurement

measurement resultattributed

to the measurandits length

length(pen)=

0.123 0.001 mmeasurement

a pen

Information worldEmpirical world


Measurement as a black boxMeasurement as a black box


measurementmeasurement result

attributedto the measurand

Measurement is a process, not its result (and “measure” is not used)Measurement is a process, not its result (and “measure” is not used)

Measurement results are property values (typically numbers with units, Measurement results are property values (typically numbers with units, together with uncertainty)together with uncertainty)

Measurement maps an empirical entity Measurement maps an empirical entity to an informational oneto an informational oneand therefore has a meta-physical role (…!)and therefore has a meta-physical role (…!)

The tradition of physical measurement has an strong empiricist connotation:The tradition of physical measurement has an strong empiricist connotation:

the measurand is the property subject to measurement,the measurand is the property subject to measurement, and property values “are in” the empirical world,and property values “are in” the empirical world, so that measurement is aimed at discovering themso that measurement is aimed at discovering them and only errors, to be reported, prevent their “perfect” discoveryand only errors, to be reported, prevent their “perfect” discovery

The traditionThe tradition


measurandwith one value

measurementestimation of

measurand valueand related error

The peculiar (?) consequence is that “perfect” measurementThe peculiar (?) consequence is that “perfect” measurementwould be an identity processwould be an identity process

Compare the generic schema:Compare the generic schema:

Challenging the traditionChallenging the tradition

measurandwith one value

estimation of measurand valueand related error

property subjectto measurement measurement


to the measurand

measurement

and the way it is interpreted according to the tradition:and the way it is interpreted according to the tradition:

What is missing here?What is missing here?

modelsmodels

While the measuring instrument interacts with the property While the measuring instrument interacts with the property subject to measurementsubject to measurement (which is empirical)... (which is empirical)...

… … the measurand is the property the measurand is the property intended to be measuredintended to be measured (as in the VIM3 definition) (which is model-dependent)(as in the VIM3 definition) (which is model-dependent)

Beyond traditionBeyond traditionBack to the generic schema:Back to the generic schema:

property subjectto measurement measurement


to the measurand

In designing and performing measurementwe do our best for our intentions to correspond to empirical states,but this is a matter of quality of models and measuring instruments,

not metaphysical assumptions

Hence, inside the black box...Hence, inside the black box...

measu

remen

t

… … there are both there are both experimentalexperimental and and informationalinformational elements elements

«We are not interested in a measuring apparatus and in the «We are not interested in a measuring apparatus and in the interaction between the apparatus and the objects being interaction between the apparatus and the objects being measured. Rather, we attempt to describe how to put measured. Rather, we attempt to describe how to put measurement on a firm, well-defined foundation»measurement on a firm, well-defined foundation»

[F. Roberts, Measurement theory, 1979][F. Roberts, Measurement theory, 1979]

A theory of measurement neglecting the role of instruments...A theory of measurement neglecting the role of instruments...

… … is indeed a generic theory of representation...is indeed a generic theory of representation...

«[there is] a certain deficiency of realism in philosophical «[there is] a certain deficiency of realism in philosophical discussions of measurement»discussions of measurement»

[O.D. Duncan, Notes on social measurement, 1984][O.D. Duncan, Notes on social measurement, 1984]

… … but measuring instruments are empirical information devicesbut measuring instruments are empirical information devices


There is nothing physics-dependent There is nothing physics-dependent in this framework...in this framework...



to the measurandmeasurement

… … which applies also to non-physical propertieswhich applies also to non-physical properties

(the interesting specificity is another one)(the interesting specificity is another one)

object underevaluation

What is the specificity?What is the specificity?

property subjectto evaluation

evaluationresult

evaluation

How is measurement characterizedHow is measurement characterizedas a specific kind of evaluation?as a specific kind of evaluation?

The information produced by measuring systems is / The information produced by measuring systems is / should be:should be:

specific to the measurand, and then independent of any specific to the measurand, and then independent of any other property of the object or the surrounding other property of the object or the surrounding environment, including the measuring system and the environment, including the measuring system and the subject who is measuring;subject who is measuring;→ this is a condition of → this is a condition of objectivityobjectivity

interpretable in the same way by different users in interpretable in the same way by different users in different places and times, because expressed in a form different places and times, because expressed in a form independent of the specific context and only referring to independent of the specific context and only referring to entities which are universally accessible;entities which are universally accessible;→ this is a condition of → this is a condition of intersubjectivityintersubjectivity

HypothesisHypothesis

Note that this is unrelated to using numbers:Note that this is unrelated to using numbers:““numerical evaluation” is NOT synonymous of “measurement”numerical evaluation” is NOT synonymous of “measurement”

How can you obtainHow can you obtain(sufficiently) objective and intersubjective information(sufficiently) objective and intersubjective information

from your evaluation process?from your evaluation process?(so that you can rely on it,(so that you can rely on it,

and you can consider it a measurement)and you can consider it a measurement)

There is nothing physics-dependent There is nothing physics-dependent in this characterization...in this characterization...

Developing and performing evaluation processes Developing and performing evaluation processes that are (sufficiently) objective and intersubjective that are (sufficiently) objective and intersubjective

is the fundamental taskis the fundamental taskof applied measurement scienceof applied measurement science

Different disciplines exploit different techniquesDifferent disciplines exploit different techniquesbut the basic endeavor is the samebut the basic endeavor is the same

The VIM, as referenceThe VIM, as reference

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

My basic message is simple:My basic message is simple:

measurement (of physical quantities)measurement (of physical quantities)is laden with stereotypes:is laden with stereotypes:please be aware of themplease be aware of them

THANK YOUTHANK YOUFOR YOUR KIND ATTENTIONFOR YOUR KIND ATTENTION

Luca MariLuca [email protected]@liuc.it

research.liuc.it/luca.mariresearch.liuc.it/luca.mari

January 23, 2018January 23, 2018

education 274c: research seminar in measurement...

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