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D. M. King and M. N. Tamburri
0
05
52
001
57
Probability of Success
(e.g., % likelihood of detecting that BW discharge does not meet regulation standards)
Cost (Millions of Dollars)
Minimal Effort
Required for 50/50
Chance of Success
High Cost/
Low Risk
Very High Cost/
Very Low Risk
Wasteful
Unattainable
A
B
C
D
E
Figure 1.
A general cost-effectiveness curve showing wasteful, unattainable, and cost-effective al-
ternatives for achieving varying levels of success.
Cost-Effectiveness Comparisons
Figure 1 presents a generalized cost-effectiveness curve that depicts the typical situation
where costs increase as an attempt is made to increase some measure of effectiveness. In the
case here, increased effectiveness means more ballast water discharge violations detected
by a verification system as reflected in higher values of (
a
) in Equation 1. In this figure,
alternatives with combinations of cost and effectiveness that are on or above the “cost-
effectiveness curve” (e.g., B, C, or E) are feasible. However, those that are above the curve
(e.g., E) are “wasteful” because there are alternatives that fall on the cost-effectiveness
curve that achieve the same or a higher level of effectiveness at a lower cost. There are no
alternatives that fall below the curve in the area marked “unachievable” because alternatives
do not exist to achieve any given level of effectiveness at a lower cost than alternatives
that are on the cost-effectiveness curve. Because there are no alternatives that fall below
the curve, and the alternatives that fall above the curve are rejected as being wasteful, the
rules for choosing the best alternative are: (1) choose the alternative that is on the curve
and provides as much effectiveness as can be afforded, or (2) decide what minimum level
of effectiveness is acceptable and choose the alternative that is on the curve at that level of
effectiveness.
Preliminary Comparison of Alternatives
The basic empirical information required to construct a precise cost-effectiveness curve for
comparing ballast water verification alternatives has not yet been developed. However, it is
possible to construct a planning-level cost-effectiveness curve to help assess and compare
these alternatives. Performing such a preliminary exercise is useful because it helps draw
attention to research questions that need to be addressed before designing a verification
program. In some cases, it can also be used to identify and screen out alternatives that
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