M. Cakmakci, N. Ortabas-Demirel, M.N. Durakbasa, G. Bas, A. Hornikova:
"Interaction Between Capability Indices and Skewness of Non-Normal Processes Using Quantile Based Estimation and Johnson Transformation";
Quality-Access to Success, Vol. 13, S5, November 2012 (2012), S. 79 - 86.

Kurzfassung englisch:
ABSTRACT: Many process capability indices have been developed for non-normal process but there has been little research about
the skewness nowadays. The aim of this research work is to investigate the interaction between capability indices and skewness by
using three estimation methods like conventional, Johnson transformation, and quantile based methods to take into consideration
symmetrical and non-symmetrical parameter of different kind of distributions such as gamma- and skew t-distribution. To
demonstrate the interaction between skewness and process capability indices Cp, and Cpk, the random data of size 100 for data sets
of gamma- and skew t-distribution for skewness ranging from 0.5, 1.0, 1.5, 1.8 to 2.0 has been generated by using of MINITAB15.
Obviously, it is seen that for the skewness parameters of the different distributions, estimation of both the gamma- and skew tdistribution
by calculating three techniques are decreasing after the "skewness parameter 1.8". Furthermore, the main findings
indicated that the skewness of the distributions have a significant influence on the methods to compute the process capability
indices, therefore on the improvement of the manufacturing process, respectively.

process capability analysis (PCA), process capability indices (PCI), non-normality, estimation methods of capability indices, interaction between skewness and capability indices.

Erstellt aus der Publikationsdatenbank der Technischen Universitšt Wien.