A description is given of the systematic errors which can be introduced when applying absolute or comparator standardization
techniques to RNAA or ENAA at irradiation sites with a deviating 1/E1+α epithermal neutron flux distribution. A simple correction formula for a≠0 is presented and a survey is given of the present
state-of-the-art for experimentala-monitoring and for the calculation or experimental determination of the effective resonance energy Ēr. Extensive error calculation leads to the conclusion that, with careful selection ofa monitors and of the nuclear data involved, the rather large errors (∼10% or more) are reduced, after correction fora, to uncertainties of about 2%.