Instrumentation & Measurement Magazine 26-1 - 12

fundamentalsmeasurement
of
Luca Mari and Dario Petri
Measurement: Knowledge from Information
about Empirical Properties
T
his paper is devoted to introducing measurement as
a process aimed at producing knowledge by attributing
values to properties of objects. Some subjects
of the paper are: measurement as a bridge from the empirical
world to the information world; the meaning of (and therefore
the information conveyed by) the key
equation measurand = measured value;
measurement scales and units; and the
distinction between qualitative and quantitative
properties.
An Overview of
Fundamentals of
Measurement:
A Justification
Measurement pervades our society and is
undoubtedly an integral part of people's
everyday life. We use measurement to acquire
information to understand, control,
and improve what we do and how we do
it. In advanced societies, measurement also
plays an increasingly vital role in a large
number of situations, being essential not
only in scientific investigation but also in
promoting social relationships and society
evolution, for example in sustaining organizational
and technological innovations,
as well as emerging technologies and multidisciplinary
research [1]. However, despite
its crucial importance in almost every field of human inquiry
and endeavor, fundamental concepts about measurement
science are still quite vague [2], and often hindered by stereotypes:
everybody benefits from the availability of information
produced by measurements and most of us do measure, but
not everybody is sufficiently knowledgeable about what is
actually at stake when a measurement is designed and performed,
and its results finally reported.
In analogy to description, judgment by experience, and
guess, measurement is a process by which a bridge is designed,
constructed, and crossed between the world of empirical
bodies, phenomena, processes, ... and the world of information
[3]. The usual, simplest version of such a bridge is in the
relation:
12
property of an object = value of a property
for example:
length of a given steel rod = 1.2345 m
(2)
where in fact the length of a given steel rod is a concrete, empirical
entity, and 1.2345 m is an abstract, information entity
(to maintain the discussion as simple as possible, we will omit
here all references to measurement uncertainty).
For sure, relation (1) does not necessarily result from a measurement,
as it could also be the outcome of an opinion or even
a guess: hence characterizing measurement as a quantitative
process is not sufficient, given that also opinion making and
guessing may be quantitative, and they are not, as such, measurements.
Rather, measurement is usually expected to be able
to provide information worth the public trust because it is " reliable,
traceable and comparable " [4]. This is the main rationale
behind maintaining a distinction between " in my opinion the
value of x is y " and " the measured value of x is y " , and thus to
socially justifying the resources devoted to perform measurements.
Hence, and particularly in our " big data " contexts in
which assessing the quality of information exploited to make
decisions is becoming a critical feature, we suggest that our society
would benefit from a widespread metrological culture [5],
[6]. To this purpose the present paper is focused on the very
fundamentals of measurement science, some of whose core
concepts are discussed here, as driven by the questions: what
are the entities in relation (1), and what kind of information do
they convey? And therefore: what kind of information does
measurement produce?
Objects, Properties, and Comparability
of Properties
We know and operate by assuming that in the empirical world
there are things, like molecules of water, steel rods, production
plants and processes, planets, tigers, companies, and countries.
In order to refer to such diverse things, instead of using
a phrase like " phenomena, bodies, or substances " , as in the
International Vocabulary of Metrology (VIM) [7], we use generically
the term " object " for short. An object usually interacts
or is made to interact with its environment in multiple ways:
we describe each of these ways of interaction as related to a
IEEE Instrumentation & Measurement Magazine
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February 2023
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Instrumentation & Measurement Magazine 26-1

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