Error Guessing

Use experience to guess where bugs like to hide.

Manual QA • Module 4 • Lesson 4
9 min read

What you'll learn

  • Use past bugs as clues.
  • Look in tricky spots first.
  • Mix guessing with planned tests.
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Error Guessing

Use experience to guess where bugs like to hide.

Big Picture

One small picture can make this idea easier to hold.

Random poke

  • No clue.
  • Low focus.
  • Easy to waste time.
  • Hard to repeat.

Smart guess

  • Uses clues.
  • Targets weak spots.
  • Saves time.
  • Easy to explain.

VerdictError guessing works best when it uses real clues.

How It Moves

Short steps make the flow easier to see.

Recall

Think about past bugs.

2

Scan

Look for weak spots.

3

Try odd input

Use strange values and paths.

4

Record

Save the pattern for next time.

Step By Step

This is the same idea, stretched across time.

  1. 1

    Clue found

    A past bug gives a hint.

  2. 2

    Weak spot chosen

    The tester picks a likely place.

  3. 3

    Odd case tried

    The tester uses a strange input or step.

  4. 4

    Pattern saved

    The team keeps the lesson for later.

One Small Model

Think of this like a tiny card you can keep in your pocket.

Bug notes

4 fields
Past bug:"Same issue seen before"
Weak spot:"Tricky screen or flow"
Odd input:"Strange value or step"
Result:"Bug appears or not"
Notes turn guesses into a repeatable habit.

Quick Check

Question 1 of 10 correct

What helps error guessing most?

Map It

One more picture helps you see where this lesson matters most.

Clue strength vs bug likelihood

Bug likelihood
High

Weak clue, low chance

No history, no sign

Strong clue, low chance

Small edge case

Weak clue, high chance

Busy screen with no data

Strong clue, high chance

Same bug happened before

Low
Weak clueStrong clue
Clue strength
The best guesses have real clues behind them.

Final Quiz

Question 1 of 30 correct

What is error guessing based on?