Is / Is-Not Analysis

Origin. Kepner-Tregoe problem analysis (1965).

Mechanism. Bounds the problem by paired specification: what is affected and what comparable thing is not; where, when, and to what extent it occurs and does not. The distinctions between the is and the is-not columns generate hypotheses; a valid cause must explain both columns.

Procedure. Four dimensions — identity, location, timing, magnitude — each with an 'is' and a closely comparable 'is not'. For each pair, ask what distinguishes them. Cross the distinctions with recent changes. A cause that explains only the 'is' is not a cause.

Applies to. Defect and failure investigation where a comparable non-failing case exists.

Limitations. Requires a genuine near-miss comparator. Where nothing comparable is unaffected, the is-not column is empty and the method provides nothing.