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attributing the obtained value to the measurand is justified by the quality of the
measuring instrument, which is expected to generate an output that is stable in
the case of repeated interactions with the object under measurement, and specifically depends on the measurand and not on other properties, i.e., the influence
properties. The fact that in this sense the measuring instrument has a limited
quality is acknowledged in terms of a non-null instrumental uncertainty (JCGM,
2012: 4:24), which is inversely related to the instrument’s accuracy (see Sect.
3.2.1). For example, the thermometer used to measure the temperature of a body
could be sensitive also to the temperature of the environment, and therefore
could produce an indication affected by instrumental uncertainty due to its
dependence on properties other than the measurand. In the case of reading comprehension ability, if different students were asked questions by different judges,
and these judges expressed the (same) questions in different ways, this would be
an example of instrumental uncertainty.
• Interaction uncertainty. Finally, the interaction between the object under measurement and the measuring instrument can alter the state of the object itself.
This may occur when acquiring information on physical properties—the socalled loading effect—and it is even more usual for psychosocial properties, as
for example in most cases of interviews, in which a respondent may be prompted
by interview questions to consider issues in a new way. This is acknowledged in
terms of a non-null interaction uncertainty. In the case of temperature measurement, a sufficiently small body might change its temperature due to its interaction with an initially colder or warmer thermometer, thus corresponding to an
interaction uncertainty. In the case of educational testing, examinees who are
asked to respond to a given set of test questions arranged from most to least difficult might conceivably perform worse, on average, than examinees asked to
respond to the exact same set of questions arranged from least to most difficult,
if their confidence is affected by their experience with the first few questions.
Another well-known example in human science measurement relates to “stereotype threat”, where people from different sociocultural groups, who may have
different assumptions regarding the overall likelihood of success of individuals
from their own group on the instrument, tend to respond in ways that are sensitive to those beliefs, especially if their identity as members of the relevant group
is made psychologically salient (see, e.g., Steele & Aronson, 1995).
While this classification offers a rich, multidimensional perspective on measurement uncertainty, given the aim of providing an overall indication of the quality of
the information produced by the measurement such components eventually need to
be combined.
3 Technical and cultural contexts for measurement systems
attributing the obtained value to the measurand is justified by the quality of the
measuring instrument, which is expected to generate an output that is stable in
the case of repeated interactions with the object under measurement, and specifically depends on the measurand and not on other properties, i.e., the influence
properties. The fact that in this sense the measuring instrument has a limited
quality is acknowledged in terms of a non-null instrumental uncertainty (JCGM,
2012: 4:24), which is inversely related to the instrument’s accuracy (see Sect.
3.2.1). For example, the thermometer used to measure the temperature of a body
could be sensitive also to the temperature of the environment, and therefore
could produce an indication affected by instrumental uncertainty due to its
dependence on properties other than the measurand. In the case of reading comprehension ability, if different students were asked questions by different judges,
and these judges expressed the (same) questions in different ways, this would be
an example of instrumental uncertainty.
• Interaction uncertainty. Finally, the interaction between the object under measurement and the measuring instrument can alter the state of the object itself.
This may occur when acquiring information on physical properties—the socalled loading effect—and it is even more usual for psychosocial properties, as
for example in most cases of interviews, in which a respondent may be prompted
by interview questions to consider issues in a new way. This is acknowledged in
terms of a non-null interaction uncertainty. In the case of temperature measurement, a sufficiently small body might change its temperature due to its interaction with an initially colder or warmer thermometer, thus corresponding to an
interaction uncertainty. In the case of educational testing, examinees who are
asked to respond to a given set of test questions arranged from most to least difficult might conceivably perform worse, on average, than examinees asked to
respond to the exact same set of questions arranged from least to most difficult,
if their confidence is affected by their experience with the first few questions.
Another well-known example in human science measurement relates to “stereotype threat”, where people from different sociocultural groups, who may have
different assumptions regarding the overall likelihood of success of individuals
from their own group on the instrument, tend to respond in ways that are sensitive to those beliefs, especially if their identity as members of the relevant group
is made psychologically salient (see, e.g., Steele & Aronson, 1995).
While this classification offers a rich, multidimensional perspective on measurement uncertainty, given the aim of providing an overall indication of the quality of
the information produced by the measurement such components eventually need to
be combined.
3 Technical and cultural contexts for measurement systems