> For the complete documentation index, see [llms.txt](https://www.bilancarbone-methode.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://www.bilancarbone-methode.com/english/4-accounting/4.4-methode-destimation-des-incertitudes/4.4.1-pourquoi-des-incertitudes.md).
# 4.4.1 - Why uncertainties?
Source: Pexels
{% hint style="info" %}
As a reminder, the emissions from each emission source of the organisation are estimated as follows:
Emission from a source = [Activity data](/english/4-accounting/4.2-methode-de-collecte-des-donnees-dactivite.md) x [Emission factor](/english/4-accounting/4.3-methode-de-selection-des-facteurs-demission.md) = [Result](/english/4-accounting/4.5-profil-demission.md) ± [Uncertainty](/english/4-accounting/4.4-methode-destimation-des-incertitudes.md)
{% endhint %}
Since estimates and measurements inherently carry a margin of error, the vast majority of scientific methods tend to associate values called uncertainties with the results of measurements or estimates.
These uncertainties lead to a 95% confidence interval, i.e. an interval \[Value 1; Value 2] within which the true value of what is being measured or estimated has a 95% probability of lying.
The Bilan Carbone® method allows [uncertainties to be determined](/english/4-accounting/4.4-methode-destimation-des-incertitudes/4.4.2-comment-les-determiner.md) both qualitatively and quantitatively.
Taking into account the uncertainties associated with activity data and emission factors and calculating their resulting effect on estimated GHG quantities aims to help organisations identify priorities for improving the quality of this data, and therefore to implement [data collection and carbon accounting improvement actions](/english/5-transition-plan/5.2-construction-du-plan-daction.md#les-differentes-categories-dactions) thereafter. The values of uncertainties must also be taken into account when analysing results and developing the transition plan. The ultimate objective is to optimise the reliability of future inventories and to guide decision-making appropriately.
Quantitative uncertainties can be propagated across the different emission categories in the assessment or even across the entire assessment, to arrive at a 95% confidence interval. It should be noted that the uncertainty propagated across the entire assessment is of limited relevance as it provides little useful information for decision-making. A more detailed analysis of uncertainties, category by category and emission source by emission source, is far more relevant for the continuous improvement of the approach.
***
*Do you have a comprehension question?* [*Consult the FAQ*](/english/annexes/faq.md)*. The method is living and therefore subject to change (clarifications, additions): find the* [*change log here*](/english/readme/historique-et-suivi-des-modifications.md)*.*
---
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