The IPCC Tier 1 Method for combining uncertainties in inventory data (i.e., parameters) is to use the error propagation method (i.e., first order), which can be summarized by the equations below:

E : Emission estimate
A : Activity
F : Emission factor
U : Uncertainty (half the 95% confidence range in percentage points)

Product Rule

Summation Rule

The error propagation method has limitations, in that it assumes normality in the input probability distribution functions and cannot easily deal with correlations between datasets or across time.

Click here for Chapter 6 “Quantifying Uncertainties in Practice” in the IPCC Good Practice Guidance. Additional guidance for uncertainty analysis for LULUCF can be found in Chapter 5.2 of the LULUCF Good Practice Guidance report here.