Chapter 4 – Test Analysis & Design
Classification Tree – ISTQB Definition
Last Updated: July 12, 2026 · SoftwareTestPilot QA Team
Official ISTQB Definition
A tree showing equivalence partitions hierarchically, used as the basis for the classification tree method of test design.
In simple words
A tree that breaks each input into partitions and sub-partitions so you can combine them systematically.
Exam tip
The classification tree method is a structured alternative to ad-hoc combining of partitions.
Related terms
- Equivalence PartitioningGroup inputs that the system should treat identically, then pick one value from each group. That way you cover behaviour without testing every possible value.
- 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.
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