Principles of Uncertainty Communication

This text is a summary from the section Reporting uncertainty analysis in scientific assessments SO 15

Communicating uncertainty aims to increase the transparency of the scientific assessment process and to provide the risk managers with a more informed evidence base by reporting on the strengths and weaknesses of the evidence.

Transparency is one of EFSA’s basic principles and has important implications for risk communication. A transparent approach to explaining how an organisation works, its governance and how it makes its decisions, is intended to build trust. Communications should clearly convey the most important areas of uncertainty in the scientific assessment, whether and how these can be addressed by the assessors and decision-makers, and the implications of these remaining uncertainties for public health. Messages about uncertainty need to be based on information that is provided in EFSA’s scientific assessments. EFSA’s communications should be designed to ensure the results of its work (including its assessment of risk and uncertainty) are correctly understood by its audience, which is the objective of the Communication of Uncertainty GD.

Types of assessment

Assessments must clearly identify sources of uncertainty and characterise their impact on the conclusion. The assessors should try to express the expert’s uncertainty in the conclusion, the overall uncertainty, quantitatively using %probability or a probability distribution. In reporting an uncertainty analysis, the Uncertainty Analysis GD describes some differences depending on the type of assessment. For standardised assessments it should mention the standard procedure was followed and a confirmation of the absence of non-standard uncertainties. In standardised assessments with non-standard uncertainties, the reporting should include how these were considered in the assessment. For other assessments, the uncertainty analysis should be reported with consideration for time constraints in urgent assessments. Depending on the type of assessment, decision-makers or legislation may require specific reporting formats, such as qualitative descriptors or unqualified conclusions. In cases where practical certainty cannot be achieved, assessors should report inconclusive findings and comply with documentation requirements.

Overall uncertainty

A concise summary of the overall uncertainty, suitable for the executive summary, should provide a simplified quantitative expression of the combined effect of identified sources of uncertainty. Assessors should ensure compatibility between the reporting of uncertainty analysis and the assessment conclusions, revising both if necessary.

In some assessments, information on the main contributors to uncertainty may be useful for decision-makers, informing further actions such as data gathering and refinement of the assessment.

Unquantified uncertainties

The assessment conclusion should include a clear statement of quantified uncertainty and, if applicable, a description of any unquantified uncertainties. The latter should be described in terms of their nature, cause, effects, difficulty in quantification, assumptions made, and suggestions for reduction or better characterisation. When there are unquantified uncertainties, words implying magnitude or likelihood should be avoided.