From ecoinvent to the lognormal PDF
Three inputs are necessary from the data provider to determine the parameters of the lognormal distribution: the deterministic value, the basic uncertainty and the pedigree matrix.
Going from the deterministic value to mu is straightforward: this value is taken as equal to mu*. In ecoEditor and ecoQuery, mu is called "Arithmetic mean of log-transformed data". The deterministic value is also called "Geometric mean" in those tools.
mu = ln(deterministic value)
Then, the basic uncertainty is chosen. This value reflects the fact that even a "perfect" data is uncertain: there are fluctuation over time, errors in measurements, etc. The table 10.3 of data quality guideline provides for values, depending on the type of exchange and process modelled. In ecoEditor and ecoQuery, this value is called "Variance of log-transformed data". The field "Standard deviation (SD95)" is equal to exp((Variance of log-transformed data)^0.5)^2, a value that is not used anywhere in the rest of the calculation.