Dear team,
It is really great that we can access the Pedigree scores directly now, and that we can calculate the additional uncertainty associated with this additional uncertainty. I have two observations, one of which may be a problem:
1) In a user-defined dataset, if one defines a distribution in the "Uncertainty" field, and then clicks in the "Data quality entry" field, the entered uncertainty information is not carried over in the "basic uncertainty". That is fine, once we know. I guess that since it is possible to export the "total" uncertainty to the uncertainty field, we would end up with a loop if it was then fed back in the Data quality entry field. So all good.
2) When looking at ecoinvent data, however, it seems that the uncertainty that is accounted for is only the basic uncertainty, without any consideration for the additional uncertianty associated with the pedigree scores. Looking at a very precise example: cryolite input in `aluminium production, primary, ingot | aluminium, primary, ingot | cut-off, U | CA-QC`. In the original ecoSpold, we have:
Lognormal (Geometric mean=0.0004, Variance of log-transformed data=0.0006, Arithmetic mean of log-transformed data=-7,824, Standard deviation=1.0502, CI/2wP, half range of confidence interval=1.2286, Variance of data with pedigree=0.0106) Pedigree matrix: 1 1 4 5 1
==>The basic uncertainty, expressed as the variance of the underlying normal, is 0.0006. As gsigma: 1.0247973619913604. This is the value reported in openLCA "uncertainty" field for this exchange.
==> The additional uncertainty, expressed as the variance of the underlying normal, is 0.01 (using the ecoinvent pedigree matrix). As gsigma, this is 1.1051709180756477.
==> The total uncertainty, expressed as the variance of the underlying normal, 0.0106, or 1.1084429706226131 as gsigma. Note that this is the value that is reported as gsigma in the "Data quality entry" page as total uncertainty, and that basic uncertainty is assumed to be nil in this page.
So, to sum up: (1) the uncertainty considered in uncertainty calculation seems to be uncertainty without pedigree, (2) the basic uncertanty displayed in the "Data Quality entry" is not correct (it is displayd as 1), and (3) the geosigma in the "Data Quality entry" is indeed the total, but is not calculated from the displayed data and is not used in the uncertainty field.
Hope this is clear and that it helps :/
Pascal
