ABSTRACT
Good safety management also includes keeping a close watch on trends and developments in accident statistics, statistics on near misses, and other indicators of changing in the risk level. In some cases, identifying trends can be based purely on plotting of the data and observing any changes. However, since the number of accidents fortunately is low, the statistics can show large variation from one year to the next, without this necessarily meaning that there is a definite trend. To analyze such data properly, we therefore need a variety of statistical techniques that can help us determine if variations are just random or represent a trend and determine the uncertainty in the frequencies and probabilities that we can calculate from the data. This chapter describes some selected statistical methods that can be used for this purpose, and illustrate with examples how they are used in practice.
