Process capability indices in software testing

For software process capability, see capability maturity model and isoiec 15504. The capability indices can be calculated manually, although there are several software. Process capability indices are only meaningful for processes that are stable in a state of statistical control. They are unitless values so that you can use them to compare the capability of different processes.

Defects occurrence during software development process is a common. Process capability voice of the customer voice of the process it is an expression of how well your process performs relative to the voc. Effective approach to quality control for smallmedium software companies. The concept of process capability pertains only to processes that are in statistical control.

In simple words, it measures producers capability to produce a product within customers tolerance range. Process capability calculations with nonnormal data in the. How to assess process capability using minitab 17 youtube. Various capability indices are presented in this section. Testing process performance based on capability index cpk with. There are many other types of sigma estimates and often statistical software programs. How to calculate cp and cpk learn to calculate process. Minitab is the worlds leading statistical software for six sigma and statistics education. It differs from process capability in that process performance only applies to a specific batch of material. Process performance index basically tries to verify if the sample that you have generated from the process is capable to meet customer ctqs requirements. Capability indices help to change the focus from only meeting requirements to continuous improvement of the process.

Process capability index cpk process capability index cpk is a statistical tool, to measure the ability of a process to produce output within customers specification limits. This module discusses the process capability indices that are commonly used as baseline measurements in the measure phase and in the control phase. Based on the test, we develop a simple and practical procedure for inplant. Cpk is a short term process index that numerically describes the within subgroup or potential capability ppk is long term indicator of a process assuming it was analyzed and stays in control. Process capability and capability index cp and cpk presentation pdf available. But to calculate any process capability indices you assume stability of your process. In field of pharmacy the various test must be carried out for the new drug or the formulation. Metrics, organization baselines, process capability analysis, ad gof tests, quality. Capability indices are ratios of the process spread and specification spread. Generally you use this when a process is under statistical control. Testing quality assurance using process capability indices cp u.

How to measure process capability and process performance. The index takes into consideration the fact that your data is maybe not centered. If you have a destructive test such as tensile testing, then you will get one reading per. It shows how closely a process is able to produce the output to its overall specifications. Process capability analysis for normal distributions cp index the cp index is the most widely used capacity index. Issues with cp, cpk, pp, ppk process capability indices. It can be calculated only when usl and lsl are both speci ed. However, analysis of nonnormal data with a pci can result in false indicators. Process capability cp is a statistical measurement of a processs ability to. This often happens with a mature process that has been around for a while. The spc software that we use is proficient by infinityqs, and so far as ive.

Capability analysis is an excellent tool to demonstrate the extent of an improvement made to a process. And it is a prediction of how well your process will meet customer requirements in the future. A process is a unique combination of tools, materials, methods, and people engaged in. Process capability index cpk is the measure of process capability. Process capability indices cp and cpk evaluate the output of a process in. Pdf process capability and capability index cp and cpk. Want to know how to measure the process performance of your project.

Process capability index cpk has been widely used in the. It can summarize a great deal of information simply, showing the capability of a process, the extent of improvement needed, and later the extent of the improvement achieved. You can test how centered a system is by comparing cp to cpk. Process capability cp, cpk and process performance pp. Journal of statistical computation and simulation, vol 82 no 2 pp 27 9 292. Determing the process capability indices, pp, ppk, cp, cpk, cpm. In both cases we want to try to verify if the process can meet to meet customer ctqs requirements. Testing quality assurance using process capability indices cp u and cp l.