Developing a Precision and Severity Monitoring System for CEC Performance Tests 2004-01-1892
The Coordinating European Council, CEC, develops performance tests for the motor, oil, petroleum, additive and allied industries. In recent years, CEC has moved away from using round robin programmes (RRP's) for monitoring the precision and severity of test methods in favour of regular referencing within a test monitoring system (TMS). In a TMS, a reference sample of known performance, determined by cross-laboratory testing, is tested at regular intervals at each laboratory. The results are plotted on control charts and determine whether the installation is and continues to be fit to evaluate products. Results from all laboratories are collated and combined to monitor the general health of the test.
The TMS approach offers considerable benefits in terms of detecting test problems and improving test quality. However, the effort required in collating data for statistical analysis is much greater, and there are technical difficulties in determining precision from TMS data.
This paper describes the test monitoring framework that has been developed and how it fits into the CEC test development process. Its statistical properties are evaluated and recommendations for the control-chart limits are formed. Some comparisons are made with the LTMS (Lubricant Test Monitoring System) used in North America.
CEC has carried out a pilot project to assess the feasibility of running a web-based database for a bench test. The results of this were encouraging and a full trial on selected bench tests is being carried out in 2004.