Of more assistance to the creation ab initio of Level C descriptions of
lesser-known species has been biogeographical work [12] and agronomic
work [24] on the use of graphical relationships based on decimal indices
from 0.0 to 1.0. These Level C sketches of responses of species to individual
factors have been used quite widely, but the approach has not so far
stimulated the production of formal sets of sketches of the responses of species
to a large number of factors. One reason for this may be the tendency to predict
performance by multiplying all the indices together to obtain an overall
prediction of performance. This can produce very erroneous results [15].