5.4.2.3 Examples of Weighting-Scaling Checklists
BEES
Battelle Environmental Evaluation System (BEES) is one of the best known weighting-scaling checklists. Originally developed for water resource project, BEES has been modified by various EIA practitioners to suit to their specific projects. BEES was developed in 1972 at Battelle Columbus Laboratory, Ohio for the U.S. Bureau of Reclamation (Whitman et al. 1971, Dee et al. 1972, Dee et al. 1973).

One of the most important characteristics of BEES is that it arranges environmental quality indicators hierarchically. The scheme of hierarchy employed allows classification of the major areas of environmental concern into Categories, components and parameters. Four levels of information is used in BEES:
Level 1
Most general information
ENVIRONMENTAL CATEGORIES
Level 2
Intermediate information
ENVIRONMENTAL COMPONENTS
Level 3
Specific information
ENVIRONMENTAL PARAMETERS
Level 4
Most specific information
ENVIRONMENTAL MEASUREMENTS

Four major environmental categories recognised are ecology, environmental pollution, aesthetics, and human interest. These four categories are broken down into 18 components and finally into 78 parameters. For example the ecology category is subdivided into three components: species and populations, habitats and communities and ecosystems. Similarly environmental pollution, aesthetics and human-interest categories have been subdivided into four, six and five environmental components respectively. Each of the environmental components is again subdivided into appropriate number of environmental parameters. Information about the state of each parameter is gathered by obtaining appropriate measurement of the parameter.

Quality of a parameter is indicated by environmental measurements. Measurements are quantified data, obtained from fieldwork or secondary data. Frequently more than one measurement is used to obtain a parameter value. Spatial and temporal considerations are included into parameter estimate by some complex methods (Warner 1973).

BEES identifies impacts by examining the parameter estimates obtained through explicit environmental measurements. Since environmental parameters are measured in different units (such as hectare, mg/l, concentration ratio, ppm, etc.), it is difficult to summarise or arrive at an overall evaluation of the net environmental impact of a project. To overcome this difficulty, BEES utilises a commensuration technique comprising the following three steps:
1. All parameter estimates are transformed into their corresponding environmental quality.
2. Parameters are assigned weights in proportion to their relative importance. These are termed parameter importance units (PIU).
3. The environmental quality of the parameters are multiplied by their PIUs to obtain the common units, - environmental impact units (EIU).

Environmental Quality
Recognising the fact that environmental quality ranges between extremely bad to very good, BEES transforms the parameter estimates into environmental quality units ranging from 0 to 1, where 0 denotes extremely bad quality and a value of 1 means a very good quality. This way, BEES is capable of accounting for any change that is beneficial or adverse. Moreover since all the parameter estimates are converted to a common unit of environmental quality using an interval scale ranging from 0 to 1 it is possible to compare different parameters on a common base to express environmental impacts in commensurate units.

Value function curves are used to transform parameter estimates into environmental quality. As has been discussed before a value function relates the measured or estimated values of parameters to appropriate levels of environmental quality. An example of a value function curve is given in Figure 5.2.

Parameter Weights
BEES recognises that only a part of the total environment is represented by an environmental parameter. Together these parts form the environmental system. BEES further recognises that all the parameters are not of equal importance. In order to 'reflect the relative importance of the parameters as indicators of the degree' to which the projects may 'disturb or enhance the dynamic stability of man's relationship' with the environment, all the 78 parameters are assigned relative weights. These weights are expressed in Parameter Importance Units (PIU) and are based on a total score of 1000 (Dee et al. 1972). The parameter importance values are linked to the relationship of the parameters to the environmental system and therefore, the PIU values are project independent. This narrows down the scope of individual bias to influence the assessment.

Subjective value judgements of several selected individuals were quantified to arrive at the relative importance of the parameters in the BEES. Two weighting techniques, 'ranked pairwise comparison technique' and the 'Delphi technique', were used for importance - weighting of the parameters.

The EIA study team uses the PIUs already assigned and hence they cannot have their own weights to reflect their views and background. BEES, therefore, allows bias free estimates which are reproducible.

By keeping the weights constant BEES attempts to minimise the emotion generated during a project analysis, making objective evaluation of alternatives possible.