198
known to be involved in a measurement” (JCGM, 2012: 2.48). As we show below,
there are at least two kinds of models that could fit this description:
• A model of the measuring instrument behavior, with respect to the environmental
properties that influence the relation between the property being measured and
the instrument indication
3
• A model of the measurand, with respect to the way the measurand is affected by,
and more generally related to, other properties
4
Though both are relevant for obtaining a final result, these models are in principle
distinct (while of course this does not prevent the possible influence of the measurement procedure on the model of the measurand, which could be changed by taking
into account information acquired from previous measurements). An exploration of
the distinction between these two (kinds of) models and their relations will lead us
to a better understanding of the role of models both of and in measurement.
7.2.1 Recovering a meaningful distinction between direct
and indirect measurement
The term “direct measurement” does not have a single inherent meaning and it is not
trademarked, of course: to our knowledge Campbell did not use it; Albert de Forest
Palmer characterized it as “the determination of [the value] by direct observation of
the measured quantity, with the aim of a divided scale or other indicating device
graduated in terms of the chosen unit” (1912: p. 11), and Ellis might have been the
first to include it in a structured analysis of measurement, though with the not-soclear characterization that “direct measurement is any form of measurement which
does not depend upon prior measurement” (1968: p. 56). Were the idea of direct
measurement intended as designating a model-free form of measurement, it should
simply be dismissed, given the acknowledgment that purely empirical and modelfree measurement is not possible.
Rather, we propose to recover a meaningful distinction between direct and indirect measurement by restarting from the definition in IEC 60050/Electropedia of
: “method of measurement in which the value of
a measurand is obtained directly, without the necessity for supplementary calculations based on a functional relationship between the measurand and other quantities
actually measured” (IEC: def.311-02-01). Admittedly, the definition is circular,
since is defined in terms of directly obtaining something. A
3 This is related to what is referred to as the measurement model part of a structural equation model
(SEM), or a measurement model for short in the context of structural equation modeling (SEM;
see, e.g., Skrondal & Rabe-Hesketh, 2004). SEMs are a popular class of statistical models used in
the human sciences, although such models have a number of different purposes.
4 This is related to what is referred to as the structural model part of the structural equation model
(SEM), or structural model for short.
7 Modeling measurement and its quality
known to be involved in a measurement” (JCGM, 2012: 2.48). As we show below,
there are at least two kinds of models that could fit this description:
• A model of the measuring instrument behavior, with respect to the environmental
properties that influence the relation between the property being measured and
the instrument indication
3
• A model of the measurand, with respect to the way the measurand is affected by,
and more generally related to, other properties
4
Though both are relevant for obtaining a final result, these models are in principle
distinct (while of course this does not prevent the possible influence of the measurement procedure on the model of the measurand, which could be changed by taking
into account information acquired from previous measurements). An exploration of
the distinction between these two (kinds of) models and their relations will lead us
to a better understanding of the role of models both of and in measurement.
7.2.1 Recovering a meaningful distinction between direct
and indirect measurement
The term “direct measurement” does not have a single inherent meaning and it is not
trademarked, of course: to our knowledge Campbell did not use it; Albert de Forest
Palmer characterized it as “the determination of [the value] by direct observation of
the measured quantity, with the aim of a divided scale or other indicating device
graduated in terms of the chosen unit” (1912: p. 11), and Ellis might have been the
first to include it in a structured analysis of measurement, though with the not-soclear characterization that “direct measurement is any form of measurement which
does not depend upon prior measurement” (1968: p. 56). Were the idea of direct
measurement intended as designating a model-free form of measurement, it should
simply be dismissed, given the acknowledgment that purely empirical and modelfree measurement is not possible.
Rather, we propose to recover a meaningful distinction between direct and indirect measurement by restarting from the definition in IEC 60050/Electropedia of
a measurand is obtained directly, without the necessity for supplementary calculations based on a functional relationship between the measurand and other quantities
actually measured” (IEC: def.311-02-01). Admittedly, the definition is circular,
since
3 This is related to what is referred to as the measurement model part of a structural equation model
(SEM), or a measurement model for short in the context of structural equation modeling (SEM;
see, e.g., Skrondal & Rabe-Hesketh, 2004). SEMs are a popular class of statistical models used in
the human sciences, although such models have a number of different purposes.
4 This is related to what is referred to as the structural model part of the structural equation model
(SEM), or structural model for short.
7 Modeling measurement and its quality