THE THEMATIC ASSESSMENT REPORT ON INVASIVE ALIEN SPECIES AND THEIR CONTROL
46SUMMARY FOR POLICYMAKERS
APPENDIX 1
Communication of the degree
of confidence
Figure SPM A 1 The four-box model for the qualitative communication of confidence. 
Confidence increases towards the top-right corner, as suggested by the increasing strength of shading. Source: IPBES (2016).12
Further details of the approach are documented in the IPBES Guide on the Production of Assessments.
13
Established 
but incomplete
Inconclusive
Well established
LEVEL OF AGREEMENT
Unresolved
CERTAINTY SCALE
QUANTITY AND QUALITY OF EVIDENCE
Low Robust Low
High High
In the methodological assessment regarding the diverse 
conceptualization of multiple values of nature and its 
benefits, including biodiversity and ecosystem functions and 
services, the degree of confidence in each main finding is 
based on the quantity and quality of evidence and the level 
of agreement regarding that evidence (Figure SPM.A1).
12. IPBES (2016): Summary for Policymakers of the Assessment Report on 
Pollinators, Pollination and Food Production of the Intergovernmental 
Science-Policy Platform on Biodiversity and Ecosystem Services. Potts, 
S.G., Imperatriz-Fonseca, V. L., Ngo, H. T., Biesmeijer, J. C., Breeze, T. D., 
Dicks, L. V., Garibaldi, L. A., Hill, R., Settele, J., Vanbergen, A. J., Aizen, M. 
A., Cunningham, S. A., Eardley, C., Freitas, B. M., Gallai, N., Kevan, P. G., 
Kovacs-Hostyanszki, A., Kwapong, P. K., Li, J., Li, X., Martins, D.J., NatesParra, G., Pettis, J.S., Rader, R. and Viana, B.F. (eds.). IPBES secretariat, 
Bonn, Germany. http://doi.org/10.5281/zenodo.2616458.
13. IPBES (2018): IPBES Guide on the Production of Assessments. Secretariat 
of the Intergovernmental Science-Policy Platform on Biodiversity and 
Ecosystem Services, Bonn, Germany. Available at: https://ipbes.net/guideproduction-assessments.
The evidence includes data, theory, models and expert 
judgement.
Well established: there is a comprehensive metaanalysis or other synthesis or multiple independent 
studies that agree.
Established but incomplete: there is general 
agreement, although only a limited number of studies 
exist; there is no comprehensive synthesis, and/or the 
studies that exist address the question imprecisely.
Unresolved: multiple independent studies exist but 
their conclusions do not agree.
Inconclusive: there is limited evidence and a 
recognition of major knowledge gaps.
SUMMARY FOR POLICYMAKERS
19SUMMARY FOR POLICYMAKERS
BACKGROUND
Table SPM 2 Options for strengthening the governance of biological invasions at national, 
regional and global scales. 