6
J. Wittmann
as if in a control station. The expert observer interprets the dynamics of the
different indicator values as an image of the real system and its dynamics and
draws conclusions about the future behavior of the system. The measured values
are therefore not interpreted in the actual sense as indicators, but as current values
of system variables that determine dynamics.
A significant difference to system modelling must be noted at this point: The
dynamic courses of the indicators are exclusively visualized and must be interpreted
by the observer himself. Relationships between the individual variables are not
explicitly specified in the sense of a model, but can only be assumed by attentive
observation of the functional processes. However, the internal structure of the
observed system always remains hidden. Findings about the structure as well as
predictions about future system behavior remain pure hypotheses in the mind of the
observers; they cannot be derived from the set of indicators. Here lies a substantial
difference to the structural models (glass box), as they are set up in the system
modelling for example by systems of differential equations.
2.2 Structural Alternatives for Indicators
Main confusing fact defining and using indicators seems the definition of the
functionality of the indicator. Not only the reachability of a value seems to be of
importance but also the aggregating and valuating character of an indicator. With
the applications of Sect. 1 in mind and together with the differentiation of the
application types from Sect. 2.1, there is a differentiation concerning the functions of
an indicator easily possible that leads to the following three levels of functionality:
2.2.1 Level 1: Observation and Transmission
The intention is to observe a certain system or model quantity. If this quantity
is not measurable directly, transmission becomes necessary. Transmission means
taking the indicator value instead of the value of the hidden or less accessible model
quantity.
A very simple example should illustrate the distinction between the different
functional levels when using indicators: a box of muesli is given together with the
question of how high the proportion of fruits and cereals is. The box is opaque,
so that a direct answer to the question is not possible. An indirect measure must
be found. In this case, the different specific gravity of the proportions is used to
calculate the quotient between the weight of the box and its volume. This value
serves as an “indicator” for the ratio of grain to fruit in the interior. The indicator
value thus provides information about a system quantity that is inaccessible to the
black box (Fig. 1).
J. Wittmann
as if in a control station. The expert observer interprets the dynamics of the
different indicator values as an image of the real system and its dynamics and
draws conclusions about the future behavior of the system. The measured values
are therefore not interpreted in the actual sense as indicators, but as current values
of system variables that determine dynamics.
A significant difference to system modelling must be noted at this point: The
dynamic courses of the indicators are exclusively visualized and must be interpreted
by the observer himself. Relationships between the individual variables are not
explicitly specified in the sense of a model, but can only be assumed by attentive
observation of the functional processes. However, the internal structure of the
observed system always remains hidden. Findings about the structure as well as
predictions about future system behavior remain pure hypotheses in the mind of the
observers; they cannot be derived from the set of indicators. Here lies a substantial
difference to the structural models (glass box), as they are set up in the system
modelling for example by systems of differential equations.
2.2 Structural Alternatives for Indicators
Main confusing fact defining and using indicators seems the definition of the
functionality of the indicator. Not only the reachability of a value seems to be of
importance but also the aggregating and valuating character of an indicator. With
the applications of Sect. 1 in mind and together with the differentiation of the
application types from Sect. 2.1, there is a differentiation concerning the functions of
an indicator easily possible that leads to the following three levels of functionality:
2.2.1 Level 1: Observation and Transmission
The intention is to observe a certain system or model quantity. If this quantity
is not measurable directly, transmission becomes necessary. Transmission means
taking the indicator value instead of the value of the hidden or less accessible model
quantity.
A very simple example should illustrate the distinction between the different
functional levels when using indicators: a box of muesli is given together with the
question of how high the proportion of fruits and cereals is. The box is opaque,
so that a direct answer to the question is not possible. An indirect measure must
be found. In this case, the different specific gravity of the proportions is used to
calculate the quotient between the weight of the box and its volume. This value
serves as an “indicator” for the ratio of grain to fruit in the interior. The indicator
value thus provides information about a system quantity that is inaccessible to the
black box (Fig. 1).