Better Statistical Test for Process Capability Index $C_p$

Cho, Joong-Jae; Lim, Soo-Duck

Journal of Korean Society for Quality Management > Volume 34(3); 2006 > Article

Journal of Korean Society for Quality Management 2006;34(3): 66-.

공정능력지수 $C_p$에 대한 효율적인 가설검정

조중재, 임수덕

충북대학교 자연과학대학 정보통계학과

Better Statistical Test for Process Capability Index $C_p$

Joong-Jae Cho, Soo-Duck Lim

Department of Information and Statistics, Chungbuk National University

ABSTRACT

The process capability indices are widely used to measure the capability of the process to manufacture items within the specified tolerance. Most evaluations on process capability indices focus on point estimates, which may result in unreliable assessments of process performance. The index $C_p$ has been widely used in various industries to assess process performance. In this paper, we propose new testing procedure on assessing $C_p$ index for practitioners to use in determining whether a given process is capable. The provided approach is easy to use and the decision making is more reliable. Whether a process is clearly normal or nonnormal, our bootstrap testing procedure could be applied effectively without the complexity of calculation. A numerical result based on the proposed approach is illustrated.

Key Words: Process Capability Index;Asymptotic Distribution;Test of Hypothesis;P-value;Bootstrap Consistency;Monte-Carlo Simulation;