Indicators and Measures - Evaluating Sustainable Development in the Built Environment - page 74

and third the conversion to 'carrying capacity' is not a precise art.
However, the output is not devalued by a broad approximation. It
indicates the comparative values between societies and allows us to
draw a reasonable conclusion.
To take another example from everyday life, we do not require a very
precise measurement of the amount of gasoline or petrol left in the tank
of our car when we are taking a journey. The purpose of the measure is
to tell us when to fill up again to avoid running out of fuel. We know
that when the tank gauge shows it is empty, with or without a warning
light, we will have enough petrol to get to a reasonably close petrol sta-
tion. When it is half-full we can gauge roughly when we will need to
fill up again on a long journey. The indicator has to be timely to be use-
ful. It would not be of much use if the petrol or gas indicator only
showed the position at the start of the journey and did not keep the
driver informed along the way. It also has to be understandable in that
it must convey the information quickly and effectively. Petrol gauges
can come in different forms such as a dial or an electronic presentation
but they have the same purpose. These rough indicators, the measures
used and the methods of presentation are sufficient for the purpose for
which we use them. If, on the other hand, we wanted to undertake a
test of the fuel efficiency of the car we might need to measure every
drop of petrol used and the precise distance covered.
Indicators therefore are presentations of measurements to suit a
particular need. They are pieces of information that summarise the
characteristics of systems or highlight what is happening in a system.
Indicators simplify complex phenomena and make it possible to gauge
the general status of a system. An indicator helps you understand
where you are, which direction you are going in, and how far you have
to go. It both assesses the current situation and gives advice for the
future. Indicators can alert you to a problem before it becomes critical
and in some case can help the user recognise what needs to be done to
resolve the problem. Sometimes it is useful to bring many indicators
together to provide a composite assessment of what is happening and
this is called an index . However, an index is an indicator in its own
right, simplifying the complexity of the indicators that form its
constituent parts.
According to the European Environment Agency (EEA) indicators
can be described as communication tools that: (a) simplify complex
issues making them accessible to a wider audience (i.e. non-experts);
(b) can encourage decision-making by pointing to clear steps in the
causal chain where it can be broken; (c) inform and empower policy-
makers and laypeople by creating a means for the measurement of
progress in tackling environmental progress (EEA, 2007). It is the capac-
ity of the indicator to reach its target audience that determines its
success. The essentials of all good indicators are therefore as follows: