Editing Ishikawa diagram (section)

== Root causes ==
[[File:blurry_photo_fishbone_diagram.svg|thumb|250px|An Ishikawa diagram breaking down possible root causes of a blurry photo]]
{{More citations needed section|date=June 2023}}
[[Root cause analysis|Root-cause analysis]] is intended to reveal key relationships among various variables, and the possible causes provide additional insight into process behavior. It shows high-level causes that lead to the problem encountered by providing a snapshot of the current situation.{{sfn | Project Management Institute | 2015 | loc=§2.4.4.2 Cause-and-Effect Diagrams | pp=20-24}}

There can be confusion about the relationships between problems, causes, symptoms and effects. Smith<ref name="Smith">Smith, Gerald F. "Determining the cause of quality problems: lessons from diagnostic disciplines." Quality Management Journal 5.2 (1998): 24-41.</ref> highlights this and the common question “Is that a problem or a symptom?” which mistakenly presumes that problems and symptoms are mutually exclusive categories. A problem is a situation that bears improvement; a symptom is the effect of a cause: a situation can be both a problem and a symptom.

At a practical level, a cause is whatever is responsible for, or explains, an effect - a factor "whose presence makes a critical difference to the occurrence of an outcome".<ref name=" Schustack ">Schustack, Miriam W. "Thinking about causality." The psychology of human thought (1988): 92-115.</ref>

The causes emerge by analysis, often through brainstorming sessions, and are grouped into categories on the main branches off the fishbone. To help structure the approach, the categories are often selected from one of the common models shown below, but may emerge as something unique to the application in a specific case.

Each potential cause is traced back to find the root cause, often using the [[5 Whys]] technique.<ref>{{Cite web|title=Fishbone diagram: Solving problems properly|url=https://www.ionos.ca/startupguide/productivity/fishbone-diagram/|access-date=2021-12-23|website=IONOS Startupguide|language=en}}</ref>

Typical categories include:

===The 5 Ms (used in manufacturing)===
{{See also|5M model}}Originating with lean manufacturing and the [[Toyota Production System]], the 5 Ms is one of the most common frameworks for root-cause analysis:<ref>{{Cite book|title=Failure mode and effects analysis (FMEAs) for small business owners and non-engineers : determining and preventing what can go wrong|last=Weeden|first=Marcia M.|year=1952|publisher=Quality Press |isbn=0873899180|oclc=921141300}}</ref>
*Manpower / Mindpower (physical or knowledge work, includes: [[kaizen]]s, suggestions)
*Machine (equipment, technology)
*Material (includes raw material, consumables, and information)
*Method (process)
*Measurement / medium (inspection, environment)
These have been expanded by some to include an additional three, and are referred to as the 8 Ms:<ref name=":0">{{Cite book|title=Reliability engineering : a life cycle approach|last=Bradley|first=Edgar|isbn=978-1498765374|oclc=963184495|date = 2016-11-03|publisher=CRC Press }}</ref>
*Mission / mother nature (purpose, environment)
*Management / money power (leadership)
*Maintenance

===The 8 Ps (used in product marketing)===
{{See also|Marketing mix}}This common model for identifying crucial attributes for planning in product marketing is often also used in root-cause analysis as categories for the Ishikawa diagram:<ref name=":0" />
*Product (or service)
*Price
*Place
*Promotion
*People (personnel)
*Process
*Physical evidence (proof)
*Performance

===The 4 or 5 Ss (used in service industries)===
An alternative used for service industries, uses four categories of possible cause:<ref>{{Cite book|title=Handbook of Lean Manufacturing in the Food Industry|last=Dudbridge|first=Michael|date=2011|publisher=John Wiley & Sons|isbn=978-1444393118|oclc=904826764}}</ref> 
*Surroundings: Refers to the environment in which the process occurs.
*Suppliers: Refers to external parties that provide inputs—raw materials, components, or services.
*Systems: Refers to the procedures, processes, and technologies used to perform the work.
*Skill: Refers to the human factor, particularly the knowledge and abilities of employees.
*Safety: Refers to physical and psychological well-being in the workplace.