| Study author | X | Y | Z | XYZ sum | Waste Collection type |
| Bovenzi | 0.08 | 0.12 | 0.21 | 0.31 | Semi-automated |
| Maeda | 0.76 | 0.79 | 1.1 |
| Manual |
| Melo | 0.17 | 0.19 | 0.43 | 0.60 | Semi-automated |
| Paschold | 0.38 | 0.42 | 0.60 | 0.99 | Automated |