Samenvatting
Control-charting has been successfully applied to two National Highway Traffic Safety Administration data systems to help improve and assure the quality of their data. This paper describes the methods used, illustrates the approach through various examples, and discusses various technical issues in applying control charts to these traffic safety data. The paper also explains the rationale of the methods in terms of statistical process control logic. Finally, an example of nonrandomly missing data is given. (A)