Logical Decisions - Classweb

Many measures represented counts of the number of impacts in
different categories. These category counts were converted to
"equivalent" counts of the most significant category. Expert
judgments were obtained of the count in each category
representing an impact equivalent to one unit in the most
significant category. These equivalent counts were then used
when developing tradeoffs involving these measures. For
example, the Prehistoric Sites measure counted the number of
sites of different types that would be affected at each reservoir
location. The experts categorized the types of prehistoric sites as
shown in Figure 10-10. The most significant category of
prehistoric sites was "residential base sites with interpretive
value." The overall level for the prehistoric sites measure was
reported in units of "equivalent number of residential base sites
with interpretive value affected." Sites in the other categories
were converted to those units by multiplying the number of sites
by the number in the last column of Figure 10-10. For example, 20
processing sites would be the equivalent of two residential bases
with interpretive value. A site with 1 residential base with
interpretive value and 20 processing sites would thus be assigned
an overall level of 1 + (20*0.1) = 3 on the prehistoric sites measure.
Sites to equal one Fraction of one
Residential Base Residential Base
Category With Interpretive Value With Interpretive Value
Residential Base With 1.0 1.0
Interpretive Value
Residential Base 1.11 0.9
Processing Site 10 0.1
Isolated Rock Art 200 0.005
Prehistoric Isolates 4000 0.00025
Figure 10-10. Equivalences for Prehistoric Sites measure in reservoir
example.
The team used this approach on the following measures:
! Prehistoric Sites,
! Historic Sites,
! Paleontological Impacts,
! Biological Habitat,
! Endangered Species,
Section 10 -- Examples 10-15