Root Cause Analysis (RCA)

How do you analyse the root cause for a defect?

As a software tester, we can use Root Cause Analysis.

Root Cause Analysis (RCA) is an approach used in software testing to analyse and identify the root causes of defects and address them, instead of treating the symptoms. If some problems happen, instead of just fixing it, we can also investigate and try to fix the underlying cause so that this kind of problems will be prevented from the next or further phases.

How to do the RCA?

Five whys technique: whose goal is to determine the root cause of a defect or problem by repeating the question “Why”. Each “why” forms the basis of the next question. For example:

6How to do RCA?
Why we've received an issue?
Why Save button is not working on users page?
Why does specific symbol affect...


The answer to these questions will give us the exact phase, where the defect actually exists. Then, we can come up with “What” question:

What will you do to avoid this in future?

So now we can prevent the same defect to arise again by implementing the answer of this question.

Why doing this?

Doing the RCA accurately helps to prevent defects in the later releases or phases.


Problem Statement: You are on your way home from work and your car stops in the middle of the road.

1. Why did your car stop?
– Because it ran out of gas.

2. Why did it run out of gas?
– Because I didn’t buy any gas on my way to work.

3. Why didn’t you buy any gas this morning?
– Because I didn’t have any money.

4. Why didn’t you have any money?
– Because I lost it all last night in a poker game.

5. Why did you lose your money in last night’s poker game?
– Because I’m not very good at “bluffing” when I don’t have a good hand.


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