This is very likely a major explanation for the reported differences. It is advisable to develop and apply a generally accepted method for making road crash costs estimates. As to output, this concerns, for instance, the way in which the data are made available for further processing and analysis. As to the use of the data, this refers to the actual use by road safety stakeholders and researchers. The possible and actual use of data by road safety stakeholders and researchers can be considered as a main indicator of the quality of a data system. The more possibilities there are to analyse the data, the better the quality of data systems.