Chapter 4 – Test Analysis & Design
Error Guessing – ISTQB Definition
Last Updated: July 12, 2026 · SoftwareTestPilot QA Team
Official ISTQB Definition
A test technique in which tests are derived on the basis of the tester's knowledge of past failures, or general knowledge of failure modes.
In simple words
Design tests based on where you (or history) know bugs usually hide — nulls, empty strings, zero, negatives, huge inputs.
Exam tip
Error guessing complements systematic techniques; it's a formal ISTQB technique, not just ad-hoc testing.
Related terms
- Exploratory TestingYou learn the product while testing it, using your experience to decide what to try next instead of following a pre-written script.
- Checklist-Based TestingWork through a curated checklist of common issues (accessibility, security, edge cases) rather than free-form exploring.
- Experience-Based TestingTests come from what you’ve seen break before — error guessing, exploratory testing, checklist-based testing.
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