Initial and post-intervention survey results, 1997 and 2000
| Effectiveness factor | County | |
|---|---|---|
| Intervention | Control | |
| *Only survey results from the control county were used for the normal annual tractor replacement rate. | ||
| Total number of farms | 949 | 1264 |
| Number surveyed | 321 (33.8%) | 322 (25.5%) |
| Number of retrofits reported in survey | 33 | 8 |
| Total number of tractors | 2752 | 3034 |
| Number of tractors with no ROPS | 1879 | 2022 |
| Percentage of tractors retrofitted | 6.0% | 1.6% |
| Normal tractor replacement rate per year | * | 4.2% |
| Cost per ROPS installation | $649 | $691 |