Analysis of dependence of decision quality on data quality

GIS professionals seem to assume that better data lead to better decisions, but how does one decide when better data lead to a better decision? An analysis to determine the effects of data quality on the quality of decisions provides criteria whether to invest in data quality improvement. This article analyzes data quality and how it influences the quality of a decision. It uses an example of an environmental engineering decision to demonstrate a general method to assess the influence of data quality on the decision. It shows that the uncertainty in aspects, which are poorly known, e.g., the necessary security levels, dominate the uncertainty of many decisions. Efforts to collect more or better data to improve the data quality of those stored in a GIS would not reduce uncertainty in the decision significantly. This result seems to be consistent with results from other studies for this very large class of decisions. The article gives a general method to assess whether collecting better data improves a decision or not.