The following description was taken from MUARC: Random drug testing in Australia, analogies with RBT, and likely effects with increased intensity levels
This paper aims to develop an analogy between RDT and the early years of RBT in Australia when intensity levels were low. This analogy is used to predict the likely effects on drug-driving among killed drivers as the number of random drug tests is increased.
Diminishing-returns type relationships were found between the annual number of RDTs and the presence of impairing drugs in killed drivers. Although the ROFT equipment and associated Police testing time is currently expensive per test, the calibrated relationships suggested that current RDT rates per licensed driver could be increased to at least 10% per year before cost-effectiveness is in doubt.
RDT has the potential to achieve significant general deterrence of drug-driving in a similar way as that achieved by best-practice RBT. While RDT is highly cost-effective at the modest levels of intensity that it is currently operated at in Australia, the analogy with RBT developed in this paper suggests that it will remain cost-effective if testing rates per licensed driver are increased up to 10% of drivers per year. However, to remain cost-effective at even higher testing rates per year, the cost per random drug test must be substantially decreased.