3.0       Frameworks for Indicator Identification and Selection

Implicit in the understanding that an indicator represents a link within a phenomenon of interest (e.g. the relationship between human health and the environment) is some conceptual interpretation of this phenomenon based on previous knowledge, experimentation, or understanding.  These models or frameworks of our comprehension of, for example, the link between water quality and human health, often represent the components in a linear fashion to more clearly articulate causal connections.  With the understanding that the situation is often more complex in reality, the model provides a framework for the organization and development of indicators at various points along the chain (Kjellstrom and Corvalan, 1996).

 

One of the most recognized of these “frameworks” of understanding is that of the “Pressure - State – Response” model developed by the Organization for Economic Co-operation and Development (OECD).  This model is based on the understanding that certain pressures on a system (e.g. release of toxic substances in the natural environment), cause certain forms of stress on components within the system (e.g. pollution of organism tissues or compartments of air, soil or water), influencing their status (e.g. levels of substances in organisms, or environmental compartments) which then elicit various forms of response (e.g. organism mortality).  From this basic model a number of others with varying levels of specificity in the chain describing links within the phenomenon have been derived and used for a variety of purposes (Figure 1). 

 

 

 

Figure 1.Examples of Commonly Used Frameworks for Indicator Organization (adapted from Eyles and Furgal, 2000)

* Bold outline indicates where most effort has been focused in indicator development and use in the past

Sources: OECD (1976); Corvalan et al. (1996); Von Schrinding (1997); Friend and Rapport (1979); Environment Canada, WHO (1996), NRC (1999)