Recommendations for Design Parameters for Central Composite Designs with Restricted Randomization
MetadataShow full item record
In response surface methodology, the central composite design is the most popular choice for fitting a second order model. The choice of the distance for the axial runs, alpha, in a central composite design is very crucial to the performance of the design. In the literature, there are plenty of discussions and recommendations for the choice of alpha, among which a rotatable alpha and an orthogonal blocking alpha receive the greatest attention. Box and Hunter (1957) discuss and calculate the values for alpha that achieve rotatability, which is a way to stabilize prediction variance of the design. They also give the values for alpha that make the design orthogonally blocked, where the estimates of the model coefficients remain the same even when the block effects are added to the model. In the last ten years, people have begun to realize the importance of a split-plot structure in industrial experiments. Constructing response surface designs with a split-plot structure is a hot research area now. In this dissertation, Box and Hunters' choice of alpha for rotatablity and orthogonal blocking is extended to central composite designs with a split-plot structure. By assigning different values to the axial run distances of the whole plot factors and the subplot factors, we propose two-strata rotatable splitplot central composite designs and orthogonally blocked split-plot central composite designs. Since the construction of the two-strata rotatable split-plot central composite design involves an unknown variance components ratio d, we further study the robustness of the two-strata rotatability on d through simulation. Our goal is to provide practical recommendations for the value of the design parameter alpha based on the philosophy of traditional response surface methodology.
- Doctoral Dissertations 
Showing items related by title, author, creator and subject.
Implications of Similarities in Instructional Design, Learner Interface Design and User Interface Design in Designing a User-Friendly Online Module Obilade, Titilola (Virginia Tech, 2015)The development of a user-friendly online module depends on the inputs, the processes and the outcomes from the user interface design, the learner interface design and the instructional design. The online module includes ...
Chadwick, Heather Riley (Virginia Tech. University Relations, 2008-09-17)Mitzi Vernon, associate professor of industrial design in Virginia Tech's College of Architecture and Urban Studies, has received a Design Educator Award and a $2,000 prize from a competition sponsored by Dell Inc.: ...
Computers in the design process : comparing creativity ratings of interior design solutions using pencil-based and computer-based design methods in schematic development Brandon, Lynn (Virginia Tech, 1994-11-12)Computer-aided design has been integrated into the design process primarily in the latter stages as a drafting tool for detailing and accuracy rather than incorporated into the early stages as a design tool for enhancing ...