Fishbone Analysis Methodology for Safety Incident Root Cause Determination

This document outlines a comprehensive methodology for conducting a fishbone analysis (also known as Ishikawa or cause-and-effect diagram) to accurately determine the root causes of safety incidents or potential hazards. This methodology emphasizes a systematic approach, involving a multidisciplinary team, thorough data collection, and unbiased analysis to identify underlying factors and develop effective preventive measures.

Team Formation and Preparation

Assemble a diverse team with relevant knowledge and experience.

Team Composition

Employees with knowledge of the work
Supervisor of the area or work
Safety officer
Health and safety committee member
Union representative (if applicable)
Employees with experience in investigations
Outside experts (if needed)

Ensure the team includes individuals with:

Knowledge of the work processes
Experience in investigative techniques
Knowledge of legal and organizational requirements
Expertise in occupational health and safety fundamentals
Skills in interviewing and data collection
Ability to analyze data and develop recommendations

Clearly define the scope and objectives of the analysis. The team should understand the specific incident or potential hazard being investigated and the desired outcomes of the analysis.

Data Collection

Gather all relevant data related to the incident or hazard.

Types of Data

Witness accounts (interview witnesses as soon as possible after the incident, keeping witnesses apart to avoid a consensus view)
Physical evidence (examine the site, preserve evidence, take photographs before anything is moved)
Relevant documents (technical data sheets, health and safety committee minutes, inspection reports, company policies, maintenance reports, past incident reports, safe-work procedures, and training reports)
Environmental conditions (weather, lighting, noise levels)
Equipment and materials involved
Work procedures in use at the time of the incident

Interviewing Techniques

Put the witness at ease
Emphasize the real reason for the investigation: to determine what happened and why
Let the witness talk and listen
Confirm that you have the statement correct
Ask open-ended questions that cannot be answered by simply "yes" or "no"
Ask about the worker's actions, environmental conditions, and potential causes of the incident
Inquire how similar incidents might be prevented in the future

Do NOT:

Intimidate the witness
Interrupt
Prompt
Ask leading questions
Show your own emotions
Jump to conclusions

Fishbone Diagram Construction

Construct the fishbone diagram to visually represent potential causes.

Identify the 'Effect'

Clearly define the problem or effect being analyzed (e.g., the specific safety incident or potential hazard). Write this effect in a box on the right side of a large sheet of paper and draw a horizontal line (the 'spine') leading to it.

Determine the 'Bones'

Identify the main categories of potential causes. Common categories include:

Manpower: Factors related to personnel, such as training, experience, physical and mental condition, and adherence to procedures.
Methods: The work procedures, processes, and practices in place at the time of the incident.
Materials: The equipment, tools, raw materials, and supplies used in the work process.
Machinery: The machines, equipment, and technology involved in the incident.
Environment: The physical work environment, including weather conditions, lighting, noise, temperature, and housekeeping.
Management: The organizational structure, policies, procedures, supervision, and communication systems.

Draw angled lines (the 'bones') extending from the spine to each category. Label each bone with the category name.

Brainstorming Potential Causes

For each category, brainstorm possible causes that could have contributed to the effect. Ask 'why' repeatedly (e.g., five whys) to drill down to the root causes. Write each potential cause as a branch off the appropriate bone. Continue to add branches and sub-branches as more causes are identified.

Analysis and Verification

Analyze the diagram to identify the most likely root causes and verify them with evidence.

Prioritize Causes

Based on the data collected, prioritize the potential causes identified in the fishbone diagram. Focus on those causes that are most likely to have contributed to the incident or hazard.

Verify Root Causes

Verify the identified root causes using the collected data. Look for direct evidence (physical or documentary) or eyewitness accounts to support each cause. Address any discrepancies or gaps in understanding by re-interviewing witnesses or gathering additional data.

Develop Recommendations

Develop specific, constructive recommendations to prevent recurrence.

Types of Recommendations

Eliminate the hazard (choose a different process, modify an existing process, substitute with a less hazardous product, improve ventilation, modify or change equipment or tools)
Contain the hazard (use enclosures, machine guards, worker booths)
Revise work procedures (modify steps, change the sequence of steps, add additional steps such as lockout procedures)
Reduce the exposure (minimize the number of times the hazard is encountered, use appropriate personal protective equipment, provide emergency facilities such as eyewash stations)

Recommendations should:

Be specific
Be constructive
Identify root causes
Identify contributing factors

Reporting and Implementation

Report the findings and recommendations and implement a corrective action plan.

Corrective Action Plan

Develop a plan for corrective action
Implement the plan
Evaluate the effectiveness of the corrective action
Make changes for continual improvement

Communicate Results

Communicate the results of the fishbone analysis and the corrective action plan to all relevant personnel, including workers, supervisors, and management. Ensure that workers are trained on any new or revised procedures.

Continuous Improvement

Regularly review and update the fishbone analysis methodology to ensure its effectiveness.

Regularly evaluate the effectiveness of the corrective actions taken and make changes for continual improvement. The fishbone analysis should be a living document that is updated as new information becomes available or as the work environment changes.