Fishbone, What-If and Checklist Analysis

Why This Topic Matters for the ASP Exam

The BCSP Associate Safety Professional (ASP) exam places heavy emphasis on hazard identification and risk assessment. Within the Safety Programs and Concepts domain, you are expected to know the common qualitative analysis tools a safety professional uses to find hazards before an incident occurs and to identify root causes after one has occurred. Fishbone (Ishikawa) diagrams, What-If analysis, and Checklist analysis are three of the most frequently tested tools because they are simple, widely used, and form the foundation for more rigorous techniques such as HAZOP, FMEA, and Fault Tree Analysis.

Understanding these methods matters for three reasons:
1. Regulatory relevance – OSHA's Process Safety Management standard (29 CFR 1910.119(e)) specifically lists What-If, Checklist, and What-If/Checklist as acceptable Process Hazard Analysis (PHA) methodologies.
2. Practical application – These are the tools you will actually use on the job for incident investigations, pre-startup reviews, management of change, and continuous improvement.
3. Exam frequency – Questions routinely ask you to distinguish between these methods, identify their strengths and limitations, and select the right tool for a given scenario.

Where These Tools Fit in Hazard Analysis

Hazard analysis techniques are often grouped as qualitative (descriptive, judgment-based) or quantitative (numerical probability and consequence). Fishbone, What-If, and Checklist analysis are all qualitative methods. They rely on the knowledge, experience, and structured brainstorming of a team rather than on failure-rate data or mathematical modeling. They are typically used early in a project, during routine reviews, or as a first pass before deciding whether a more detailed technique is warranted. Fishbone is primarily a root cause (retrospective) tool, while What-If and Checklist are primarily hazard identification (prospective) tools, though all three can be adapted to either purpose.

Part 1: Fishbone Diagram (Ishikawa / Cause-and-Effect Diagram)

What it is
The Fishbone diagram was developed by Dr. Kaoru Ishikawa in the 1960s as a quality control tool and is one of the classic Seven Basic Tools of Quality. It is a visual cause-and-effect diagram that resembles the skeleton of a fish. The head of the fish states the problem or effect (for example, an injury, a near miss, a defect, or an undesired event). The spine runs horizontally to the head, and the major bones branching off the spine represent categories of potential causes. Smaller bones attached to each category list specific contributing causes.

Common cause categories
The most frequently used category set for manufacturing and industrial safety is the 6 Ms:
• Man (People / Manpower) – training, fatigue, behavior, staffing
• Machine – equipment, tools, guarding, maintenance
• Method – procedures, work practices, supervision
• Material – raw materials, chemicals, PPE quality
• Measurement – inspection, calibration, monitoring
• Mother Nature (Environment) – weather, lighting, noise, temperature, housekeeping

Some organizations use 4 Ms (Man, Machine, Method, Material) or, in service industries, the 4 Ps (Policies, Procedures, People, Plant/Place) or 8 Ps. The exam may reference any of these; the key concept is that categories organize brainstorming so no major source of causation is overlooked.

How it works – step by step
1. Clearly define the problem statement (the effect) and write it in the head of the fish.
2. Draw the spine and label the major cause categories as bones.
3. Assemble a cross-functional team with knowledge of the process.
4. Brainstorm potential causes under each category, asking why repeatedly (often combined with the 5 Whys technique) to drill down to root causes rather than symptoms.
5. Add sub-causes as smaller branches.
6. Analyze the completed diagram, prioritize the most likely or most significant causes, and verify them with data.
7. Develop corrective actions targeting root causes.

Strengths
• Simple, visual, and easy to understand
• Encourages team participation and broad thinking
• Organizes many possible causes in a structured format
• Helps distinguish root causes from symptoms
• Inexpensive and requires no special software

Limitations
• Does not rank or quantify causes – it shows possibilities, not probabilities
• Can become cluttered on complex problems
• Relies heavily on team knowledge; a weak team produces a weak diagram
• Does not show interactions or sequence between causes (unlike a fault tree)
• Identifies potential causes that still must be verified

Typical uses
Incident and accident investigation, root cause analysis, quality improvement (Six Sigma, Lean), and continuous improvement programs.

Part 2: What-If Analysis

What it is
What-If analysis is a structured brainstorming technique in which a team of experienced personnel systematically asks questions beginning with What if...? to identify possible hazards, deviations, and their consequences. It is one of the least formal of the recognized PHA methods and is explicitly accepted under OSHA PSM 1910.119(e)(2).

How it works – step by step
1. Define the scope (a process, a piece of equipment, a procedure, or an entire facility).
2. Gather information: P&IDs, procedures, MSDS/SDS, incident history, design basis.
3. Assemble a multidisciplinary team (operations, maintenance, engineering, safety).
4. Walk through the process step by step and pose What-If questions, for example:
– What if the pump fails to start?
– What if the operator adds the wrong chemical?
– What if the relief valve is stuck closed?
– What if power is lost during the transfer?
5. For each question, document the potential consequence, the existing safeguards, a qualitative risk judgment, and recommendations.
6. Record results in a What-If table and assign action items.

A typical What-If worksheet has columns such as: What-If Question | Consequence/Hazard | Existing Safeguards | Risk Ranking | Recommendation | Responsible Party.

Strengths
• Flexible – can be applied at any stage of a project and to almost any system
• Relatively fast and inexpensive
• Encourages creative thinking about unusual scenarios
• Requires minimal specialized training
• Works well for simpler processes and for procedure reviews

Limitations
• Unstructured – quality depends entirely on the experience and imagination of the team
• Easy to miss hazards if the team does not think to ask the right question
• Results are not easily reproducible between teams
• Does not systematically examine every parameter deviation (unlike HAZOP)
• Not quantitative

Typical uses
Process hazard analysis for less complex processes, management of change reviews, pre-startup safety reviews, procedure reviews, and as a preliminary screening tool.

Part 3: Checklist Analysis

What it is
Checklist analysis uses a prepared list of questions or items based on codes, standards, regulations, industry practice, and lessons learned from past incidents. The analyst or team compares the system, equipment, or procedure against each item on the list to verify compliance and identify deficiencies. Checklists are the oldest and most widely used hazard analysis tool and are also recognized under OSHA PSM 1910.119(e)(2).

How it works – step by step
1. Select or develop a checklist appropriate to the system (for example, based on NFPA, ANSI, API, OSHA standards, or internal company experience).
2. Define the scope and gather relevant documentation.
3. Walk through the facility or review drawings and procedures, answering each checklist item (typically Yes / No / Not Applicable).
4. Document each deficiency or No answer along with its significance.
5. Develop recommendations and corrective actions.
6. Periodically update the checklist as standards change and new hazards are learned.

Strengths
• Simple, quick, and easy to use by personnel with limited analysis experience
• Consistent and repeatable – different reviewers get similar results
• Ensures compliance with known requirements and captures lessons learned
• Excellent for inspections, audits, and routine reviews
• Low cost

Limitations
• Only finds what is on the list – cannot identify new or unanticipated hazards
• Quality depends on the expertise of whoever wrote the checklist
• Can encourage a mechanical, check-the-box mindset that discourages critical thinking
• Must be kept current; outdated checklists give false assurance
• Not quantitative and provides little insight into cause-and-effect relationships

Typical uses
Pre-startup safety reviews, compliance audits, workplace inspections, confined space entry, lockout/tagout verification, contractor reviews, and PHA of well-understood, standardized processes.

Part 4: The What-If/Checklist Hybrid

Because the weaknesses of What-If (lack of structure) and Checklist (lack of creativity) are complementary, they are frequently combined into the What-If/Checklist method, which OSHA PSM lists as a distinct acceptable PHA technique. The team first brainstorms What-If questions freely, then uses a checklist to fill in gaps the brainstorming missed. This hybrid provides both creativity and completeness and is one of the most commonly used PHA methods for moderately complex processes. On the exam, if a question describes a method that combines open brainstorming with a structured list to ensure thoroughness, the answer is What-If/Checklist.

Part 5: Comparison at a Glance

Fishbone – Purpose: root cause analysis after an event or problem. Nature: visual cause-and-effect diagram. Structure: cause categories (6 Ms). Key limitation: does not rank or quantify causes. Origin: Ishikawa, quality management.

What-If – Purpose: hazard identification before an event. Nature: brainstorming with open-ended questions. Structure: loosely structured, team-driven. Key limitation: can miss hazards if the team fails to ask the right question.

Checklist – Purpose: verification against known requirements. Nature: predefined list of items. Structure: highly structured. Key limitation: only finds hazards already on the list.

How they relate to other methods
• JHA/JSA – breaks a job into steps and identifies hazards for each; task-focused rather than process- or cause-focused.
• HAZOP – uses guide words (No, More, Less, Reverse, Other Than) applied to process parameters; far more systematic and rigorous than What-If.
• FMEA – examines each component's failure modes and effects; bottom-up and component-focused.
• Fault Tree Analysis – top-down deductive logic diagram using AND/OR gates; can be quantified, unlike Fishbone.
• Event Tree Analysis – forward-looking inductive analysis of outcomes following an initiating event.

A common exam distinction: Fishbone and Fault Tree both start with an undesired event and work backward to causes, but Fault Tree uses Boolean logic gates and can be quantified, while Fishbone simply categorizes possible causes without logic relationships.

Exam Tips: Answering Questions on Fishbone, What-If and Checklist Analysis

Tip 1 – Recognize the keywords. If the question mentions cause-and-effect, Ishikawa, 6 Ms, categories of causes, or root cause diagram, the answer is Fishbone. If it mentions brainstorming, open-ended questions, or experienced team asking questions, think What-If. If it mentions compliance with standards, predetermined list, yes/no items, or repeatable by less experienced personnel, think Checklist.

Tip 2 – Know the direction of analysis. Fishbone is retrospective (looks backward from an effect to its causes). What-If and Checklist are usually prospective (look forward to identify hazards before they cause harm). Questions about incident investigation point toward Fishbone; questions about PHA, pre-startup, or management of change point toward What-If or Checklist.

Tip 3 – Memorize the classic limitations. The exam loves to ask about weaknesses. Checklist: cannot find hazards not on the list. What-If: unstructured and dependent on team experience. Fishbone: does not prioritize or quantify causes and does not show how causes interact.

Tip 4 – Remember all three are qualitative. If an answer choice claims one of these methods produces a numerical probability of failure, it is wrong. Quantification belongs to Fault Tree Analysis, Event Tree Analysis, and quantitative risk assessment.

Tip 5 – Know the OSHA PSM list. 29 CFR 1910.119(e)(2) accepts: What-If, Checklist, What-If/Checklist, HAZOP, FMEA, Fault Tree Analysis, or an appropriate equivalent methodology. Fishbone is not on this list – it is a quality/root-cause tool, not a formal PHA method. This is a frequently tested distinction.

Tip 6 – Match the tool to process complexity. Simple or well-standardized processes: Checklist. Simple to moderate processes needing creative hazard discovery: What-If or What-If/Checklist. Complex processes with many parameter interactions: HAZOP or FMEA. If a question asks for the most thorough or most systematic option and HAZOP is a choice, HAZOP beats What-If and Checklist.

Tip 7 – Watch for the hybrid. When a scenario describes combining brainstorming with a structured list to ensure nothing is missed, the answer is What-If/Checklist, not either method alone.

Tip 8 – Connect Fishbone to the 5 Whys and quality tools. Questions may frame Fishbone within Six Sigma, Lean, Total Quality Management, or Deming's continuous improvement cycle. Remember it is one of the Seven Basic Quality Tools alongside Pareto charts, histograms, control charts, check sheets, scatter diagrams, and flowcharts.

Tip 9 – Eliminate distractors. If an answer choice describes guide words applied to process parameters, that is HAZOP. If it describes AND/OR logic gates, that is Fault Tree. If it describes component failure modes and severity ratings (RPN), that is FMEA. Use these to eliminate wrong options quickly.

Tip 10 – Read for the question's actual objective. Ask yourself: is the question about finding hazards, verifying compliance, or explaining why something happened? Finding = What-If. Verifying = Checklist. Explaining = Fishbone.

Practice Questions

Question 1. A safety team investigating a forklift collision draws a diagram with the collision at the head and branches labeled People, Equipment, Procedures, Materials, Environment, and Measurement. Which technique are they using?
A. Fault Tree Analysis
B. HAZOP
C. Fishbone diagram
D. Event Tree Analysis
Answer: C. Cause categories branching toward a stated effect is the defining feature of the Ishikawa/Fishbone diagram.

Question 2. Which is the primary limitation of Checklist analysis?
A. It requires extensive quantitative data
B. It can only identify hazards included on the list
C. It is too time-consuming for routine use
D. It requires a highly specialized team
Answer: B. Checklists cannot reveal hazards that the checklist author did not anticipate.

Question 3. Which of the following is NOT listed in OSHA 1910.119(e) as an acceptable PHA methodology?
A. What-If
B. Checklist
C. Fishbone diagram
D. HAZOP
Answer: C. Fishbone is a root cause/quality tool, not a recognized PSM PHA method.

Question 4. A team reviewing a new batch mixing procedure asks questions such as What if the agitator fails during addition? and What if the wrong solvent is charged? and records consequences and safeguards. This is an example of:
A. FMEA
B. What-If analysis
C. Job Safety Analysis
D. Fault Tree Analysis
Answer: B. Open-ended questioning of possible deviations is What-If analysis.

Question 5. The main advantage of combining What-If and Checklist methods is that:
A. The result becomes quantitative
B. Creative brainstorming is supplemented by structured completeness
C. Fewer team members are required
D. It replaces the need for HAZOP on complex processes
Answer: B. The hybrid offsets the weaknesses of each method.

Key Takeaways

• All three tools are qualitative, team-based, and relatively low-cost.
• Fishbone organizes possible causes of a known effect into categories (6 Ms); it is a root cause tool from quality management and does not rank or quantify.
• What-If is flexible brainstorming using open-ended questions; its weakness is lack of structure.
• Checklist is structured verification against known standards; its weakness is that it finds only what is listed.
• What-If/Checklist combines the two and is one of the most common PHA approaches.
• What-If, Checklist, and What-If/Checklist are OSHA PSM-recognized PHA methods; Fishbone is not.
• For exam success, identify keywords, know each method's purpose and limitation, and eliminate distractors that describe HAZOP, FMEA, or Fault Tree features.