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Biologists'
Key WFD quality
assessment value
1 top of High
2 mid-High
3 High/Good
4 mid-Good
5 Good/Moderate
6 worse
Figure 3.14
Biologists' assessment values
The environmental quality which any RIVPACS predictions indicates the environmental quality of the prediction in terms
for a site relates to is the sum of the products of biologists’ of its deviation from the High/Good status boundary. We can
average assessment values in each RIVPACS end group therefore adjust the predicted value of the index by adding
and the probability of the site belonging to that end group. an amount representing its deviation from High/Good (its
The calculation is analogous to that used for prediction in predicted biologists’ assessment value), scaled according to
Table 3.5. This ‘predicted’ biologists’ assessment value the status class interval. This is shown in Figure 3.15.
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