Six-Point Avoidability Scale17 23
| Rating | Category | Description |
| 1 | Totally unavoidable | Virtually no evidence of avoidability |
| 2 | Unavoidable | Slight to modest evidence of avoidability |
| 3 | Possibly avoidable | Possibly avoidable, less than 50–50, but close call |
| 4 | Probably avoidable | Probably avoidable, more than 50–50, but close call |
| 5 | Probably avoidable | Strong evidence of avoidability |
| 6 | Totally avoidable | Virtually certain evidence of avoidability |