The outcome of this report is a targeted review of existing outlier-detection tools in the field of statistics, data mining and spatial analysis, and an examination how they can assist in the detection of errors/outliers in the ESPON Database for improved quality control. This methodological review has a clear focus on spatial analysis with respect to outlier-detection; and is complemented by worked examples on an ESPON-type data set, where chosen techniques are demonstrated. Worked examples are coded using open-source software so that the applied techniques are easily transferable.