The Logical Explanation

When we handle bug report tickets, we need to put some clear idea which describes the cause of defects. But unfortunately even we believe that the description is almost sufficient, someone asks us to give more clear idea. In this case, we need to notice that there may be some insufficiency of

logical explanation on the description. Many people will watch GM tickets. Some are high skilled, some are juniors. Considering about these circumstances to avoid time consuming and non-productive work, I recommend all the

engineer to introduce the idea of Logical Explanation.This PPT presentation simply explains what is the logical explanation. I hope everyone can

understand the points and execute immediately.

2 March 2016 Copyright 2016 Yuichi MORIWAKI 1

Logical explanationThe purpose of logical explanation is to easily make other people understand the issue and cause. And it brings quicker understanding what need to be done and who need to be the person to take action.The benefit is that we can give clear idea of what we verified to other people.

There is a box.A customer had found a bug in it, and requested you to remove it.

You check the box.

You removed it and report “a bug was removed”.

Is this logical?

2 March 2016 Copyright 2016 Yuichi MORIWAKI 2

Logical explanationYou exactly removed. You can show the removed bug as the evidence.You can show the empty box as the result of removal.

But this is not logical. Why?

First we need to understand the request of “removal”.� Even a customer requested the removal of bug which was found in a box, but from quality point

of view, this implies, we may need to check all boxes. � A customer doesn’t know how many boxes are already there.� A customer doesn’t know the reason why a bug was in a box.

Think, by what we can explain logically that “a bug has been removed”. And consider what will be the necessary actions for that?

We at least explain, how many boxes are there and how we checked & removed.And we need to explain the reason and/or possibilities of bugs.

2 March 2016 Copyright 2016 Yuichi MORIWAKI 3

Logical explanation

� We need to explain the current condition.� We need to indicate of the way how we checked and its correctness. � We need to indicate the simple result.� We need to explain the cause and/or the possible cause of this issue.� We need to explain the countermeasure for the cause.� And we need to add a conclusion.

1. Need to indicate how many boxes are there at the customer site. (current condition) In this case there are 100 boxes.

2. Need to indicate how we checked 100 boxes. We need to explain the correctness of verification methodology and prove that the process can eliminate any possibility of leakage of unchecked box.

3. Indicate the result. No need to explain the detail. Just simply explain . “No bugs have found” is OK as we already indicate 1 and 2 above.

4. Need to indicate the causes & possible causes.During the production of boxes?During storing the boxes?During transporting boxes?

:5. Indicate the countermeasure against above

possibilities.6. Just conclude

The agreement with the customer is preferable.

2 March 2016 Copyright 2016 Yuichi MORIWAKI 4

Logical explanationThe points are;

- We need to explain the preconditions.- How many boxes are there.- How many boxes need to be checked and why. - How many boxes are not the target and why.

- We need to show our correctness.- The way of checking and/or the methodology is proper and correct.

- We need to indicate the process what we have taken to check and verify can cover all the cases. There ‘s no leak of case.)

- If our way of verification can miss some cases, the customer won’t accept our result of “no bugs”.

For example; “We checked all 100 boxes at once by using 100 engineers.” The

customer probably will be satisfied with our way of checking.

But If we say, “We checked all 100 boxes one by one by a specific person

spending 100 minutes.” The customer may ask you, that “Is there any possibilities that the bug may be jumped to another box while the person is checking a box? Then, you need to explain that there are no possibilities again. As explained here, some incorrect or insufficient verification methodology brings another task. that is exactly a time consuming. We easily become tired of those customer’s indication.

2 March 2016 Copyright 2016 Yuichi MORIWAKI 5

Logical explanationAnd also the points are;

- We need to explain the causes and the possible causes.- Indicate the process of box manufacturing, storing, transporting and handling.- Inspect each processes by multiple person and multiple times.- Consolidate the information and make a list of possibilities.

- We need to show the countermeasures.- Based on the list of possibilities, we need to indicate the effective processes to avoid the

occurrence of issues or to eliminate the possibilities.- We need to explain how to manage and monitor the process.

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Think of causes and possible causes.

1. Indicate all the cases 2. Specify the cases which affect

cause and which may affect the cause.

3. Indicate the countermeasure against the causes.

4. Explain why the countermeasure is effective and show the expectations.

2 March 2016 Copyright 2016 Yuichi MORIWAKI 6

Logical explanationConsidering our concrete cases;

- When we are asked to check or analyze where the defect came from. - We need to see what is the phenomena.- We need to see what is the expected behavior or result.- We need to indicate all the cases which occurs those phenomena.

(Same as the indication of number of box)- We need to indicate the result of verification of those cases.

(Same as showing our correctness)

- In reality, we may not have enough time to indicate all the cases, but as far as it is possible, we’d better take that action.

- If we are confident enough to bring the result of one specific test, but even in that case we at least need to indicate the existence of 100 boxes and the reason why we omitted the test on remaining 99 boxes.

I killed the bug and

removed it.I’m confident

Even you are Confident, there are still 99 boxes. How can you make us confident about

NO BUGS.You at least need to explain why you can

ignore 99 boxes.

Some similar transactions are happening in handling of GM tickets between multiple parties.It is ideal if we have enough time to spend to show all the cases, but even in practical, we need to indicate preconditions, methodology of verification and reason for omission. This is the Logical Explanation.

2 March 2016 Copyright 2016 Yuichi MORIWAKI 7