Analytical distributions and statistics for managing import pathway risk using the continuous sampling plans CSP-2 and CSP-3

B, Barnes

Overview

Australia imposes regulations on goods that arrive in the country and have the potential to introduce exotic pests and diseases. Continuous sampling plans (CSP) are operational biosecurity systems commonly implemented at the border to manage risk and, simultaneously, keep regulatory inspection costs low.

Currently, CSP-1 systems are underpinned by the results and proposed design-criteria in the classical work of Dodge (1943), and CSP-2 and CSP-3 systems are underpinned by that in Dodge and Torrey (1951).

In an earlier ABARES Report (Barnes et al., 2022) we extended that foundational work for CSP-1 to include full distributions, uncertainty and inspection sensitivity, and in this paper, which supplements that work, we extend the foundational work for CSP-2 and CSP-3 in the same way. The inclusion of inspection sensitivity and uncertainty are both highly relevant to Australian border operations where samples from arriving consignments, with low but variable levels of contamination, are selected and inspected.

We provide analytical distributions and statistics for all processes for each mode and for the full cycle of each CSP system, including expressions for variance and leakage. Results, together with those from Barnes et al. (2022), provide a highly efficient and easily accessible means of designing a range of CSP schemes, increasing the information available for decisions, and having the potential to influence biosecurity outcomes and improve the reliability of operational systems.