Global parameters used in the model and sensitivity analysis. All costs are in NZ $ for 2000 (NZ $1.00 = US $0.45, UK £0.31, €0.50)
| Base value | Maximum value | Minimum value | |
|---|---|---|---|
| *The social cost of a fatality was $2280000 in December 2000 currency. From the willingness-to-pay survey, preventing one permanently disabling head injury was at least as important as preventing one fatality.24 | |||
| †In the first year of the law (1994) we assumed law enforcement costs would be double the costs of subsequent years (that is, $400000). This cost was pro rated over the percentage of cyclists in each age group (table 1). | |||
| ‡Also, including an additional $30 “other” costs of quitting cycling. | |||
| Cost of helmet (all age groups) ($) | 17.73 | 44.44 | 8.89 |
| Life of helmet (years) | 5 | 7 | 3 |
| Discount rate (%) | 5 | 10 | 0 |
| Social costs of injury with <7 days hospital treatment ($)*22 | 13309 | 15970 | 10647 |
| Social costs of injury with ≥7 days hospital treatment ($)*22 | 196360 | 235632 | 157088 |
| Law enforcement costs ($)† | Nil | 200000 | Nil |
| Head injuries averted per year due to the HWL | |||
| 5–12 years | 4.0 | 10.0 | Nil |
| 13–18 years | 10.3 | 14.0 | 6.7 |
| Adults | 28.3 | 35.0 | 22.0 |
| Number of cyclists quitting | |||
| 5–12 years | Nil | 5870 | – |
| 13–18 years | Nil | 47173 | – |
| Adults | Nil | 82890 | – |
| Costs of quitting cycling ($) | 0.00 | 19.95‡ | – |