The data requirement can be substantial and only rarely is data provided regularly on the appropriate geographical scale and with the necessary frequency. Therefore, in order to provide the necessary data basis, actual sampled data must be supplemented by estimations and modelling, all of which decrease transparency, replicability and perhaps even validity or precision. Further, the indicators and indices cover a range of complexity, from simple single species indicators to complex and modelled indices of biodiversity. All of these may be applied when linking economic activities and biodiversity.