Understanding the Features of Non-Orthogonality in Quadratic Response Surface Designs


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Authors

  • Nripes Kumar Mandal Retd. Professor, University of Calcutta, Kolkata
  • Bikas Kumar Sinha Retd. Professor, Indian Statistical Institute, Kolkata
  • Manisha Pal Adjunct Professor, St. Xavier’s University, Kolkata

https://doi.org/10.56093/jisas.v79i2.181853

Keywords:

Response surface design; Orthogonal design; Non-orthogonality measures; D-optimal design; Rotatable design.

Abstract

Orthogonality is an important concept in design of experiment. Though orthogonal designs exist for multivariate first-degree regression model, such 
designs do not exist for second- and higher-degree models. In this paper, an attempt has been made to first introduce some measures or indices to 
non-orthogonality, and then to identify designs with minimum non-orthogonality indices. It is observed that such designs are neither D-optimal nor 
rotatable. Some examples are given for second degree model with two and three factors.

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References

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Submitted

2026-07-24

Published

2026-07-24

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Articles

How to Cite

Nripes Kumar Mandal, Bikas Kumar Sinha, & Manisha Pal. (2026). Understanding the Features of Non-Orthogonality in Quadratic Response Surface Designs. Journal of the Indian Society of Agricultural Statistics, 79(2), 87-94. https://doi.org/10.56093/jisas.v79i2.181853
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