Distribution-free control chart
Early research on nonparametric control charts may be found in 1981[1] when P.K. Bhattacharya and D. Frierson introduced a nonparametric control chart for detecting small disorders. However, major growth of nonparametric control charting schemes has taken place only in the recent years[when?].
Popular distribution-free control charts
There are distribution-free control charts for both Phase-I analysis and Phase-II monitoring.
One of the most notable distribution-free control charts for Phase-I analysis is RS/P chart proposed by G. Capizzi and G. Masaratto. RS/P charts separately monitor location and scale parameters of a univariate process using two separate charts. In 2019, Chenglong Li, Amitava Mukherjee and Qin Su proposed a single distribution-free control chart for Phase-I analysis using multisample Lepage statistic.
Some popular Phase-II distribution-free control charts for univariate continuous processes includes:
- Sign charts based on the sign statistic[2] - used to monitor location parameter of a process
- Wilcoxon rank-sum charts based on the Wilcoxon rank-sum test[3]- used to monitor location parameter of a process
- Control charts based on precedence or excedance statistic
- Shewhart-Lepage chart based on the Lepage test[4] - used to monitor both location and scale parameters of a process simultaneously in a single chart
- Shewhart-Cucconi chart based on the Cucconi test[5] - used to monitor both location and scale parameters of a process simultaneously in a single chart