The rise of globalisation has led to a sharp increase in international trade, with high volumes of containers, goods and items moving across the world. Unfortunately, these trade pathways also facilitate the movement of unwanted pests, weeds, diseases, and pathogens. Each item could contain biosecurity risk material, but it is impractical to inspect every item. Instead, inspection efforts typically focus on high risk items. However, low risk does not imply no risk. It is crucial to monitor the low risk pathways to ensure that they are and remain low risk. To do so, many approaches would seek to estimate the risk to some precision, but the lower the risk, the more samples needed to estimate the risk. On a low-risk pathway that can be afforded more limited inspection resources, it makes more sense to assign fewer samples to the lower risk activities. We approach the problem by introducing two thresholds. Our method focuses on letting us know whether the risk is below certain thresholds, rather than estimating the risk precisely. This method also allows us to detect a significant change in risk. Our approach typically requires less sampling than previous methods, while still providing evidence to regulators to help them efficiently and effectively allocate inspection effort.

翻译：全球化进程的加剧导致国际贸易量急剧增长，大量集装箱、商品和物资在全球范围内流动。然而，这些贸易路径同时也成为有害生物、杂草、病害及病原体传播的通道。每件货物都可能携带生物安全风险物质，但逐一查验所有货物并不可行。当前检疫工作通常聚焦于高风险物品，但"低风险"并不意味着"零风险"。监测低风险路径以确保其始终处于低风险状态至关重要。为实现该目标，现有方法通常需要估算风险达到特定精度，然而风险越低，所需样本量越大。对于可分配有限检疫资源的低风险路径，更合理的策略是将更少样本分配给更低风险的活动。我们通过引入双重阈值来解决该问题：本方法不追求精准估算风险值，而是着重判断风险是否低于特定阈值。该方法还能有效检测风险的显著变化。与既有方法相比，本方法在显著降低采样需求的同时，仍能为监管部门提供充分证据，助其高效合理地分配检疫资源。