This document outlines levels of problem analysis and countermeasure implementation. Level 1 involves monitoring problem occurrence but not fully investigating causes. Higher levels involve more thorough root cause analysis using techniques like 5-Why, confirmation testing, and countermeasures applied more broadly. Level 5 represents the deepest analysis of root causes, most robust countermeasures, and effectiveness evaluation applied across the entire system. The document provides criteria for evaluating the thoroughness of a 5-Why analysis report.

1. 発生状況調査 要因把握 原因と対策 効果検証 水平展開
4
顧客での不具合発
生状況の把握
再現テストのよる１
次原因の確定
管理活動に対する対
策
3
不良現品の表面的
調査のみ
一つの原因に絞り
込んだ調査
システムに対する対策
2
車両への不具合製
品の影響調査
ルールとの比較によ
る要因の確定
流出原因に対する対
策
1
不良発生数量の把
握のみ
表面的発生原因の
み調査
表層発生原因に対す
る対策
不良発生有無のみ
確認
表層での何故なぜ
5
不良現品の詳細調
査及び製品仕様へ
の適合検証
４Ｍに対し、３次レベ
ルまでの要因調査
４Ｍに対し保証度５レ
ベル及び定量的対策
作業者の理解度ま
で踏み込んだ効果
検証及び更なる改
善テーマの抽出
何故なぜによる真の
原因調査（ルール決
定段階，管理系）
システム全体に対
する効果検証及び
対策に対する定量
判断
不良発生事象のみ
での真の原因調査
5 Why Level criteria

2. Status of
Problem
Grasp of the
fact (5-Why)
Cause &
countermeasure
Countermeasure
effectiveness
Horizontal
deployment
4
Grasp of detected
condition on actual
parts, site,
phenomenon.
Confirmation of root
cause by re-
occurrence test.
Countermeasure to the
quality system or
management activities.
3
Brief investigation on
actual rejected items.
Focus on one most
possible cause,
investigation in depth
to root cause.
Confirmation on
countermeasure to root
cause.
2
Investigation of
influence to vehicle
by defected items.
Compare the actual
reject to quality
standard, investigate
on occurrence.
Countermeasure to
outflow.
1
Only grasp of
rejected item and
quantity.
Some investigations
on occurrence of
reject.
Countermeasure to
occurrence.
Monitor on
reoccurrence.
Why-Why is done to
the surface level only.
5
Detail investigation
on actual rejected
items and
confirmation of
meeting to
specification
(product & process.)
Investigation on the
root cause of reject
till 3rd level to 4 M .
High assurance degree
of countermeasure to
4 M ( ex. Regulated
Pokayoke ) &
measurable
countermeasure.
Effectiveness
evaluation till related
personnel understand
& able to apply on
more improvement
items.
Extracting of root
causes by Why-Why
questioning to rule
making stage and
management area.
(Preventive actions.
Able to apply the
solution on other
operations.)
Effectiveness
evaluation to overall
system & measurable
judgment of
countermeasure.
Extracting of root
causes to the defects
occurrence
phenomenon only.
( Not enough Why-
Why, only corrective
actions. )
5-Why Level Criteria
5-Why Analysis
Prepared by : DarrenTeh
Date : 30th Jun 2004

3. 5-Why Analysis
Prepared by : DarrenTeh
Date : 30th Jun 2004
5-Why Level Criteria
1) Assist to carry out “Self-Appraisal” on 5-Why
Analysis Report.
2) When received 5-Why report from supplier or
other department, first carry out some
investigations, or shangen shugi on the problem
status and contents before simply use the
Judgment Matrix.

4. 5-Why Analysis
Prepared by : DarrenTeh
Date : 30th Jun 2004
Case Study 2

5. 5-Why Analysis
Prepared by : DarrenTeh
Date : 30th Jun 2004
Case Study 2
Group A
1) Zhu Gao Feng (TSA) (Presentation)
2) Xie Shi Jun (TSA)
3) Wang Chun Yi (SIT)
4) Chen Ting Yuan (SIT)
Group B
1) Prapon (STC)
2) Babar (SPK) (Presentation)
3) Suha (SVL)
Group C
SVL / PVL staff

6. 5-Why Analysis
Prepared by : DarrenTeh
Date : 30th Jun 2004
Use the same 5-Why reports as case study 1, and make presentation :
• Judge if the 5-Why report is analyzed appropriately according to
judgment matrix, and explain your reasons.
Case Study 2

7. 5-Why Analysis
Prepared by : DarrenTeh
Date : 30th Jun 2004
Case Study 2
Status of Problems
Grasp of The Facts (why-
why)
Cause & Countermeasure
Countermeasure
Effectiveness
Horizontal Deployment
Level 1 to 5
Discussion

9. 5-Why Analysis
Prepared by : DarrenTeh
Date : 30th Jun 2004
Conclusion
1) Implement 5-why analysis report for
defective product:
• Customer complaint
• Large volume defective
• Affect production plan
2) Submit your best 5-why analysis
report to RHQ/AQMT by 30th Nov 2004.