Robert Fidrich wrote: >>"I think systematic "scatter/errors" can be easier handle than errors caused by comparisons from various sources..."<< I think we have a many edged sword here. Systematic errors are many, and to adjust or align them all would be near impossible. Where on the other hand, comparison magnitudes from various sources (random errors) could be more easily adjusted to, thru usage of corrections (or adjustment formulae) to the data. Best Regards, Steve