Red List Index (total)

• Global
• National

\[RLI^t=1 - \frac{\sum_{i}^{n}S_i\cdot W_i}{N\cdot W_{EX}}\]Where: \(S_it\)is the number of species for category i, \( w_i\)is the weight of category i (1 for ¿almost threatened¿ up to 5 ¿Extinct¿), \N\) is the total number of species considered and \(W_{EX}\)is the weight for category ¿Extinct¿. For the calculation of this indicator the wild species present in Spain are considered according to the data of the Spanish Inventory of Natural Heritage and Biodiversity for which its category of global IUCN threat has been determined. In order for year-on-year comparisons to be made, the indicator requires comparison of the same set of species each year. For this reason, when determining the category of threat of new species, the indicator is reviewed retrospectively, assuming that the most recent assessment applies since the first set of species was evaluated. \(W_{EX}\)Dollars_parentesis_3

• Three-year periodicity.

• The above is based on theoretically calculating how far we are from the extinction of our species. To do this, compare the number of species in each threat category by weighting each category (from 1 for 'almost threatened' to 5 'Extinct') with the hypothesis that all species were extinct. To put it in 'positive' the indicator is presented as the difference up to 1. That is, how close we are to complete conservation. Thus the closer to 1, the better the species are and the closer to 0, the closer to extinction. To calculate the indicator it is therefore necessary to have the threat categories with IUCN methodology; since an ODS indicator has taken into account the categories of global IUCN threat, this allows not only comparison with other countries but also periodic repetition and to establish a trend for the species considered by keeping up to date the lists of the categories of global IUCN threat.