4. Concluding remarks

The most important message with this subject paper is that NFA organization and implementation are important matters to consider. Sometimes the theoretical issues related to NFA design are considered the most important parts in the field of NFAs, although in practice in most cases the performance and reliability of an NFA will depend on a number of issues related to the implementation, which in turn depends on the organization. Strict routines need to be established in all phases in order to avoid surveyor- or analysis-induced errors in data that dramatically may reduce the usability of the information from the NFA. For example, varying systematic error levels between years may lead to severely erroneous policy conclusions. Such errors thus must be avoided - through careful set up of the organization and through rigorous implementation of the NFA.