INDperform provides an implementation of the 7-step approach suggested by Otto et al. (2018) to validate ecological state indicators and to select a suite of complimentary and well performing indicators. This suite can be then used to assess the current state of the system in comparison to a reference period. See also the website: https://saskiaotto.github.io/INDperform/
The package builds upon the tidy data principles and offers functions to
identify temporal indicator changes,
model relationships to pressures while taking non-linear responses and temporal autocorrelation into account, and to
quantify the robustness of these models.
These functions can be executed on any number of indicators and pressures. Based on these analyses and a scoring scheme for selected criteria the individual performances can be quantified, visualized, and compared. The combination of tools provided in this package can significantly help making state indicators operational under given management schemes such as the EU Marine Strategy Framework Directive.
INDperform offers function that can be applied individually to some extent but mostly build upon each other to follow the 7-step approach. They can be grouped into 3 broad categories. For demonstration purposes the package provides a dataset of food web indicators and pressure variables in the Central Baltic Sea (modified from Otto et al., 2018).
The following functions implement the first five steps of the 7-step
validation approach and model each IND as a function of time or a
single pressure variable using Generalized Additive Models (GAMs)
(based on the
To show the model diagnostics or complete model results use the functions:
Among the 16 common indicator selection criteria, five criteria relate to the indicators' performances and require time series for their evaluation, i.e.
8. Development reflects ecosystem change caused by variation in manageable pressure(s)
9. Sensitive or responsive to pressures
10. Robust, i.e. responses in a predictive fashion, and statistically sound
11. Links to management measures (responsiveness and specificity)
12. Relates where appropriate to other indicators but is not redundant
In this package, the scoring scheme for these criteria as proposed by
Otto et al. (2018) serves as basis for the quantification
of the IND performance (see the scoring template table
crit_scores_tmpl). Sensitivity (criterion 9) and
robustness (criterion 10) are specified into more detailed sub-criteria
to allow for quantification based on statistical models and rated
individually for every potential pressure that might affect the IND
directly or indirectly.
However, the scoring template can easily be adapted to any kind of state indicator and management scheme by modifying the scores, the weighting of scores or by removing (sub)criteria.
The following functions relate to the indicator performance scoring (used in this order):
For examining redundancies and selecting robust indicator suites use (in that order):
Two approaches based on trajectories in state space to determine the current state of the system in comparison to an earlier period as reference using the selected IND suite (state space = n-dimensional space of possible locations of IND variables)
1. Calculation of the Euclidean distance in state space of any dimensionality between each single year (or any other time step used) and a defined reference year:
2. Given the identification of a reference domain in state space, more recent observations might lie within or outside this domain. The convex hull is a multivariate measure derived from computational geometry representing the smallest convex set containing all the reference points in Euclidean plane or space. For visualization, only 2 dimensions considered (dimension reduction through e.g. Principal Component Analysis suggested).
To learn more about the framework, see
Otto, S.A., Kadin, M., Casini, M., Torres, M.A., Blenckner, T. (2018) A quantitative framework for selecting and validating food web indicators. Ecological Indicators, 84: 619-631, doi: https://doi.org/10.1016/j.ecolind.2017.05.045
Report bugs at https://github.com/saskiaotto/INDperform/issues
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