Table 2

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 valueMaximum valueMinimum 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 $30 “other” costs of quitting cycling.
Cost of helmet (all age groups) ($)17.7344.448.89
Life of helmet (years)573
Discount rate (%)5100
Social costs of injury with <7 days hospital treatment ($)*22133091597010647
Social costs of injury with ≥7 days hospital treatment ($)*22196360235632157088
Law enforcement costs ($)†Nil200000Nil
Head injuries averted per year due to the HWL
    5–12 years4.010.0Nil
    13–18 years10.314.06.7
Number of cyclists quitting
    5–12 yearsNil5870
    13–18 yearsNil47173
Costs of quitting cycling ($)0.0019.95‡