It is often difficult to derive the uncertainty of the amount of a specific input or output from the information available to you. The pedigree matrix offers a simple, standard procedure to quantify the uncertainty of those values.
To use this feature, select either lognormal or normal as your distribution type, right-click the field SD^2 or 2*SD, and select Edit Pedigree. A window will pop-up where a basic uncertainty value is given (based on expert panel judgments for the kind of input and output considered). Here you can assess the data quality based on 6 indicators.
(Please note that Sample size is no longer used by ecoinvent v3. However, because it was used in SimaPro in the past, it was not removed in more recent releases.) Once you click OK, the Basic and Total uncertainty will be recalculated based on your input. For more details on this feature, press F1 or go to Help> SimaPro Help.