Chapter 4 – Test Analysis & Design
Orthogonal Array Testing – ISTQB Definition
Last Updated: July 12, 2026 · SoftwareTestPilot QA Team
Official ISTQB Definition
A systematic, statistical way of testing pairwise interactions by deriving a representative subset of test combinations from an orthogonal array.
In simple words
A math-based way of picking a small, balanced set of test cases that still covers every pair of input values.
Exam tip
Orthogonal arrays give the same coverage as pairwise with a mathematically proven minimum number of tests.
Related terms
- Pairwise TestingInstead of testing every combination, test every pair of inputs at least once — catches most combination bugs with far fewer tests.
- Combinatorial TestingA family of techniques (pairwise, orthogonal arrays, classification tree) that shrink an exploding combination space to a manageable subset.
- Classification TreeA tree that breaks each input into partitions and sub-partitions so you can combine them systematically.
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