Virginia Tech
The application of a single control chart for dependent variables in multivariate quality control
Abstract
dc:description.abstractMost control charts monitor only one quality characteristic. There are, however, many manufactured products for which good quality requires meeting specifications in more than one physical characteristic. Typical practice when dealing with multiple quality characteristics is to take a separate sample for each characteristic and then create individual univariate control charts which are independently monitored. This method can result in errors due to not accounting for the effects of correlation. In order to avoid these errors, an alternate approach to multivariate quality control problems is proposed and studied here. The original problem is converted into a univariate problem by using the following transformation: y=Σ a<sub>i</sub>x<sub>i</sub> i where αi = weighting coefficient for the i<sup>th</sup> quality characteristic X<sub>i</sub> = represents the i<sup>th</sup> quality characteristic This transformation retains sensitivity to changes in the original quality variables. The resulting univariate quality control model takes into account the sampling error probabilities for each of several candidate hypotheses. The probabilities of correctly diagnosing process shifts when an out-of-control state occurs are calculated and tabulated as are the probabilities that the model will signal when an out-of-control state occurs.
Degree
thesis:*- Name thesis:degree_name
- Master of Science
- Level thesis:degree_level
- masters
- Discipline thesis:degree_discipline
- Industrial Engineering and Operations Research
- Department dc:contributor.department
- Industrial Engineering and Operations Research
- Grantor dc:publisher
- Virginia Tech
- Year dc:date.issued
- 1990
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Hanson, Robert Alexander
- Committee members dc:contributor.committeemember
-
- Nachlas, Joel A.
- Schmidt, J. William
- Fabrycky, Wolter J.
Rights
dc:rights- Statement dc:rights
-
- In Copyright
- Licence dc:rights.uri
- Language dc:language.iso
- en
Identifiers
dc:identifier.*- Dc Identifier Other
- etd-05022009-040726
- OAI identifier oai:identifier
- oai:vtechworks.lib.vt.edu:10919/42422