Eco-indicator 99

Ranking

Next to weighting, the panel members were asked to rank the three damage categories according to their perceived importance. The triangle concept will be used to demonstrate the result of the ranking performed by the respondents.

When a panel member states that Human Health (H) is more important than Ecosystem Quality (E) and that Ecosystem Quality is more important than Resources (R), we can interpret this as:

1. Human Health (H) has a weight higher than 33%. Otherwise E or R would by definition get the highest factor.
2. Resources has a weight that is lower than 33 %. Otherwise it would be higher than either H or E.
3. Ecosystem Quality (E) has a weight lower than 50%. Otherwise it would be higher than H if the weight of R is zero.

This reasoning can be shown graphically in the triangle as a grey area in figure 1:

With this reasoning the areas for all combinations that have been answered by 75 (out of 82) respondents can be plotted. In figure 2 all areas are combined in one triangle with the frequency in which an area or part of an area was chosen by the respondents. This figure must be interpreted with care, as the fields overlap.

This can be seen as the sum of all figures is about three times as high as the number of people that have answered the question. The figure 52 in the trapezium a little left from the center does not indicate that 52 respondents choose the weights in this area, but that this area is included in the (much larger) area of each respondent.

In spite of this, the picture shows quite clearly that in the ranking Resources receive a relatively low weight, while Ecosystem Quality and Human Health receive approximately equal weights. This is in accordance with the results of the weighting procedure.

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