## 4 Results
The stratification analysis made it possible to develop the simplified weighted Ishikawa diagram shown in Figure 7. The final version of the diagram presented contains the most critical causes of marine accidents. Figure 6: Lorenz diagram and stratification analysis. \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Sub-Cause** & **Absolute Weight** & **Accumulated Weight** & **Reference Field** \\ \hline
4.1.2. Non-compliance with certified system(s) & 0.206 & 0.206 & 11.124 \\
4.4.2. Port inspections & 0.165 & 0.371 & 19.663 \\
2.2. Inappropriate situational system & 0.150 & 0.521 & 27.092 \\
2.2.1.2. Perceived pain & 0.150 & 0.671 & 34.221 \\
2.1. Adverse social system & 0.150 & 0.821 & 41.050 \\
4.2.3. Inadequate monitoring & 0.138 & 0.959 & 46.991 \\
3.1.2. No regular inspections & 0.131 & 1.090 & 52.320 \\
2.1.1.1. Expectation of punctuality & 0.125 & 1.215 & 57.105 \\
2.1.1.2. Expectation of speed & 0.125 & 1.340 & 61.640 \\
2.1.2. Life stresses & 0.125 & 1.465 & 65.925 \\
2.2.1. Employee fatigue & 0.125 & 1.590 & 69.960 \\
2.2.2. Stress caused by an external stimulus & 0.125 & 1.715 & 73.745 \\
4.2.1. Errors in the delegation of tasks & 0.115 & 1.830 & 76.860 \\
1.1. Adverse meteorological conditions & 0.113 & 1.943 & 79.663 \\
2.1.2.1. Death of a loved one & 0.113 & 2.056 & 82.240 \\
2.2.3.2. Hand strain & 0.113 & 2.169 & 84.591 \\
2.2.3.3. Uncomfortable posture & 0.113 & 2.282 & 86.716 \\
4.2. Errors in the management of the ship’s crew & 0.103 & 2.385 & 88.245 \\
2.1.3. Social role & 0.099 & 2.484 & 89.424 \\
2.2.1.3. Strenuous hydrometeorological conditions & 0.099 & 2.583 & 90.405 \\
2.2.2.2. Noise & 0.099 & 2.682 & 91.188 \\
2.1.2.2. Illness of a close relative & 0.090 & 2.772 & 91.476 \\
2.2.2.4. Personal space & 0.088 & 2.860 & 91.520 \\
3.1. Improper operation & 0.088 & 2.948 & 91.388 \\
3.2. Ship failures & 0.088 & 3.036 & 91.080 \\
2.1.1. Social pressure & 0.075 & 3.111 & 90.219 \\
4.1. Voyage planning errors & 0.069 & 3.180 & 89.040 \\
4.1.1. Incomplete documents & 0.069 & 3.249 & 87.723 \\
2.2.2.3. Lighting & 0.062 & 3.311 & 86.086 \\
4.3. Incomplete ship operating report & 0.058 & 3.369 & 84.225 \\
5.1. Cargo shifting & 0.058 & 3.427 & 82.248 \\
4.4.3. Flag state inspections & 0.055 & 3.482 & 80.086 \\
4.4.1. Internal audits by the company or external & 0.055 & 3.537 & 77.814 \\ audits by the chartrerer & 0.050 & 3.587 & 75.327 \\
2.1.1.3. Expectation of responsibility & 0.050 & 3.637 & 72.740 \\
2.2.1.1. Long working hours & 0.050 & 3.687 & 70.053 \\
2.2.2.1. Air quality & 0.050 & 3.737 & 67.266 \\
2.2.3. Ergonomic aspects & 0.050 & 3.787 & 64.379 \\
2.2.3.4. Annoying vibrations & 0.050 & 3.833 & 61.328 \\
4.4. Inaccurate inspection of the ship & 0.045 & 3.878 & 58.170 \\
2.1.2.3. Harm (own) & 0.044 & 3.922 & 54.908 \\ \hline
3.1.1. Non-compliance of operational activities with the requirements of the company and IMO & 0.044 & 3.966 & 51.558 \\ regulations & 0.038 & 4.004 & 48.048 \\
2.1.2.5. Risk of dismissal & 0.038 & 4.042 & 44.462 \\
3.2.4. Main engine failure & 0.035 & 4.077 & 40.770 \\
5.2. Drifting wreck & 0.025 & 4.102 & 36.918 \\
2.2.3.1. Repetitiveness of activities & 0.025 & 4.127 & 33.016 \\
3.2.5. Failure of automatic equipment & 0.025 & 4.152 & 29.064 \\
3.2.7. Damage to pipelines and fittings & 0.025 & 4.177 & 25.062 \\
3.2.3. Damage to the deck equipment & 0.023 & 4.200 & 21.000 \\
4.2.2. Inadequate staff appraisal system & 0.023 & 4.223 & 16.892 \\
5.3. Terrorist attack & 0.017 & 4.240 & 12.720 \\
2.1.2.4. Loneliness & 0.015 & 4.255 & 8.510 \\
3.2.6. Failure of auxiliary machinery in the engine & 0.012 & 4.267 & 4.267 \\ room & 0.010 & 4.277 & 0.000 \\
3.2.1. Damage to the navigation system & 0.010 & 4.267 & 4.267 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Results of the stratification analysis.