A method of performing statistical analysis, including outlier detection and anomalous behaviour identification, on large or complex datasets (including very large and massive datasets) is disclosed. The method allows large statistical datasets (which may be distributed) to be analysed, assessed, investigated and managed in an interactive fashion as a part of a production system or for ad-hoc analysis. The method involves first processing the data into histograms and storing them in a manner that is capable of rapid retrieval. Then these histograms can be manipulated to provide conventional statistical results in an interactive manner. It also provides a method whereby these histograms can be updated over time, rather than being re-processed each time they are to be used. It has particular benefit to two class probabilistic systems, where results need to be assessed on the basis of false-positives and false-negatives.
