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质量控制七工具 — 鱼骨图

2008-06-19 12:25阅读：

http://blog.sina.cn/dpool/blog/u/1397413471

鱼骨图是由日本管理大师石川馨先生所发展出来的，故又名石川图。鱼骨图是一种发现问题“根本原因”的方法，它也可以称之为“因果图”。鱼骨图原本用于质量管理。它是利用“头脑风暴法”，集思广益，寻找影响质量、时间、成本等问题的潜在因素，然后用图形的形式来表示的一种用的方法，它能帮助我们集中注意心搜寻产生问题的根源，并为收集数据指出方向。
 鱼骨图的三种类型：
  1. 整理问题型鱼骨图（各要素与特性值间不存在原因关系，而是结构构成关系）
  2. 原因型鱼骨图（鱼头在右，特性值通常以“为什么……”来写）
对策型鱼骨图（鱼头在左，特性值通常以“如何提高/改善……”来写）
因果图作图步骤

  1. 确定要研究分析的质量问题和对象，既确定要解决的质量特性是什么。将分析对象用肯定语气（不标问号）写在图的右边，最好定量表示，以便判断采取措施后的效果。
  2. 确定造成这个结果和质量问题的因素分类项目。影响工序质量的因素分为人员、设备、材料、工艺方法、环境等；再依次细分，画大枝，箭头指向主干，箭尾端记上分类项目，并用方框框上。
  3. 把到会者发言、讨论、分析的意见归纳起来，按相互的相依隶属关系，由大到小，从粗到细，逐步深入，直到能够采取解决问题的措施为止。将上述项目分别展开：中枝表示对应的项目中造成质量问题的一个或几个原因；一个原因画一个箭头，使它平行于主干而指向大枝；把讨论、意见归纳为短语，应言简意准，记在箭干的上面或下面，再展开，画小枝，小枝是造成中枝的原因。如此展开下去，越具体越细致，就越好。
  4. 确定因果图中的主要、关键原因，并用符号明显的标出，再去现场调查研究，验证所确定的主要、关键原因是否找对、找准。以此作为制订质量改进措施的重点项目。一般情况下，主要、关键原因不应超过所提出的原因总数的三分之一。
  5. 注明本因果图的名称、日期、参加分析的人员、绘制人和参考查询事项。
做因果图的一个重要内容就是要收集大量的信息，而许多信息是靠人们主观想象和思维得到的。


作因果图的注意事项


  1. 要充分发扬民主，把各种意见都记录、整理入图。一定要请当事人、知情人到会并发言，介绍情况，发表意见。
  2. 主要、关键原因越具体，改进措施的针对性就越强。主要、关键原因初步确定后，应到现场去落实、验证主要原因，在订出切实可行的措施去解决。
  3. 不要过分的追究个人责任，而要注意从组织上、管理上找原因。实事求是的提供质量数据和信息，不互相推托责任。
  4. 尽可能用数据反映、说明问题。
  5. 作完因果图后，应检查下列几项：图名、应标明主要原因是哪些等、文字是否简便通俗、编译是否明确、定性是否准确、应尽可能地定量化、改进措施不宜画在图上。
  6. 有必要时，可再画出措施表。
为了要将原因有系统的整理与分类，管理或是质量管理学上所应用的技巧可套入此架构，当成是思考与分类的基础。常见的有6M、8P与4S原则

  1. The 6 M's：Machine, Method, Materials, Measurement, Man and Mother Nature (Environment) （适用于制造业）
  2. The 8 P's：Price, Promotion, People, Processes, Place / Plant, Policies, Procedures & Product (or Service) （适用于行政管理与服务业）
  3. The 4 S's：Surroundings, Suppliers, Systems, Skills（适用于服务业）
当然，先前不同文章所提到分类法，包括4M（工程问题规划与解决的诀窍 - 4M问题分析法）、PEST或STEEPLE、PMI项目管理的五大流程与九大知识领域、市场营销4C与4P、6管（包括产、销、人、发、财、资）等亦可应用于原因的建构与分解。
图例1：
质量控制七工具 <wbr>— <wbr>鱼骨图
图例2：
质量控制七工具 <wbr>— <wbr>鱼骨图
其他补充（英文）

What is a Cause and Effect Diagram? Description

The Cause and Effect Diagram (Fishbone Diagram) from Japanese quality control statistician Kaoru Ishikawa is a graphical technique that can be used in teams to identify and arrange the causes of an event or problem or outcome. It graphically illustrates the hierarchical relationship between the causes according to their level of importance or detail and a given outcome. Also called: Ishikawa Diagram.

Origin of the Fishbone Diagram. History

The Fishbone Diagram was invented by Professor Kaoru Ishikawa of Tokyo University, a highly regarded Japanese expert in quality management. He first used it in 1943 to help explain to a group of engineers at Kawasaki Steel Works how a complex set of factors could be related to help understand a problem.

Usage of the Cause and Effect Diagram | Fishbone Diagram. Applications

  • Concentrating on a complex problem in a team effort. Compare: 8D Problem Solving
  • Identify all causes and the the root causes for a specific effect, problem, or condition.
  • Analyze and relate some of the interactions among the factors affecting a particular process or effect.
  • Enable corrective action.

Steps in creating an Ishikawa Diagram. Process

  1. Explain the purpose of the meeting. Then identify, and clearly state, and agree on the problem or effect to be analyzed.
2. Position a whiteboard or flipchart so that everyone can see it. Draw a box containing the problem or effect on the right side of the diagram with a horizontal spine.
  1. Conduct a Brainstorming session. As a first draft, for the main branches you can use the following Categories:
    • Services industry: the 8 Ps: People, Product/Service, Price, Promotion, Policies, Processes, Procedures, Place/Plant/Technology.
    • Manufacturing: the 6 Ms: Manpower, Methods, Measurements, Machinery, Materials, Mother Nature (environment).
    • Use the above categories by asking for example: What are the People issues affecting/causing the problem?
4. Identify the main causes contributing to the effect being studied. This could be done applying a Pareto Analysis (80/20 rule) or a Root Cause Analysis.
5. These main causes become the labels for the sub branches of your diagram.
  1. For each major sub branch, identify other specific factors which may be the causes of the effect. Ask: Why is this cause happening?
  2. Identify increasingly more detailed levels of causes and continue organizing them under related causes or categories.
  3. Analyze the diagram.
  4. Act on the diagram. Remove the causes of the problem. Generic systematic approaches for this are the Deming Cycle or RACI.

Strengths the Cause and Effect Diagram. Benefits

  • Helps to find and consider all possible causes of the problem, rather than just the ones that are most obvious.
  • Helps to determine the root causes of a problem or quality characteristic in a structured way.
  • Encourages group participation and utilizes group knowledge of the process.
  • Helps to focus on the causes of the issue without resorting to complaints and irrelevant discussion.
  • Uses an orderly, easy-to-read format to diagram cause-and-effect relationships.
  • Increases knowledge of the process by helping everyone to learn more about the factors at work and how they relate.
  • Identifies areas for further study where there is a lack of sufficient information.

Limitations of the Ishikawa Diagram. Disadvantages

  • Not particularly useful for extremely complex problems, where many causes and many problems are interrelated.

Assumptions of the Fishbone Diagram. Conditions

  • A problem is composed of a limited number of causes, which are in turn also composed of sub causes.
Distinguishing these causes and sub causes is a useful first step to deal with the problem.

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