NOTE: 0 = no change/difference from Alternative 1; –1/1 = marginal, or minor change from Alternative 1; and –2/2 = moderate or major change from Alternative 1. The index values contained in this table only contain ordinal information and can only be used to make ordinal comparisons. For example, an index value of 2 is better than a value of 1, but not necessarily twice as good. Therefore, it is not possible to obtain meaningful summary information by performing numerical operations (e.g., adding, subtracting, averaging) using two or more of the index values.
SOURCE: National Marine Fisheries Service, 2001a.