A note on efficient audit sample selection

Auditing is a widely used method for quality improvement, and many guidelines are available advising on how to draw samples for auditing. However, researchers or auditors sometimes find themselves in situations that are not straightforward and the standard sampling techniques are not sufficient, for example when a selective sample has initially been audited and the auditor desires to re-use as many cases as possible from this initial audit in a new audit sample that is representative with respect to some background characteristics. In this paper, we introduce a method that selects an audit sample that re-uses initially audited cases by considering the selection of a representative audit sample as a constrained minimization problem. In addition, we evaluate the performance of this method by means of a simulation study and we apply the method to draw an audit sample of establishments to evaluate the quality of an establishment registry used to produce statistics on energy consumption per type of economic activity.