| | Variable | Type | Feature |
| | Dependent variable (output) | Type of accident | Nominal | Fall (1), wipeout (2), hit (3), cut (4), narrowness (5), crash (6) | | Independent variable (input) | Gender | Nominal | Male (1), female (2) | | Day of the week | Weekdays (1), weekend (2) | | Location | Seoul (1), capital area (except for Seoul) (2), etc. (3) | | Nationality | Korean (1), foreigner (2) | | Season | Spring (1), summer (2), | | | Autumn (3), winter (4) | | Time | 06–12 hour (1), 12–18 hour (2), 18–22 hour (3), 22–06 hour (4) | | Type of employment | Regular (1), nonregular (2) | | Type of occupation | Management (1), engineering (2), labor (3), operation (4) | | Type of project | Residential and commercial (1), public and healthy (2), etc. (3) | | Age | Numerical | Integer (17–83) | | Project duration | Integer (1–13,752) | | Project scale | Integer (0.1–2,000) | | Rate of process | Real number (5–90) | | Workforce | Integer (5–3,000) | | Year of service | Real number (0.8–30) |
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