Re-ordering policies for inventory systems with a fluctuating economic environment – Using economic descriptors to model the demand process
本文识别GDP和经济政策不确定性两个关键经济因素，将经济环境划分为不同状态，并利用连续时间马尔可夫链建模波动，发现考虑经济依赖性能显著改善库存系统绩效，尤其对科技行业效果最明显。
Customer demand is highly dependent on external environmental factors that are mainly economic in nature. We build on the financial literature to identify two key economic factors that impact the demand process, which are the gross domestic product (GDP) and the economic policy uncertainty (EPU). We accordingly categorize the economic environment into states that jointly capture different realizations of the GDP and EPU. We resort to data from the technology, automotive and oil industries to further validate the state categorizations by illustrating the relationship/dependency between the economic states and the demand process. We utilize a regularization technique to capture the fluctuation in the economic environment by a continuous time Markov Chain. We observe that the demand rates are dependent on the economic environment and accounting for this dependency improves the performance of the inventory system, especially in the technology industry. We numerically investigate the impact of the fluctuations on inventory control systems with continuous (s, S) inventory control policies. Algorithmic approaches, based on matrix representations of the system, are presented to compute the inventory performance measures. Our numerical study shows that savings are highest for the technology industry where the demand process is highly dependent on fluctuations in the economic environment.