A class of nearly orthogonal arrays

Xuan Lu, William Li, Miao Xie

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Orthogonal arrays with mixed levels are very useful in factorial experiments when factors with different numbers of levels are to be investigated. However, one limitation associated with mixed-level orthogonal arrays is that many of them require a large number of runs. In such cases, nearly orthogonal arrays - which generally use fewer runs by slightly relaxing the requirement of orthogonality - may be useful. We propose a definition of nearly orthogonal arrays of strength m, extending the concept of orthogonal arrays of strength m. We focus on the nearly orthogonal arrays involving 2- and 3-level factors with small run sizes. Some useful arrays are tabulated for practical use. These designs are shown to have nice statistical and combinatorial properties.

Original languageEnglish (US)
Pages (from-to)148-161
Number of pages14
JournalJournal of Quality Technology
Issue number2
StatePublished - Apr 2006


  • Nearly Orthogonal Array of Strength m
  • Orthogonal Array
  • Strength


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