Dissertation
Essays on vulnerability of global supply chains
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Summer 2022
DOI: 10.25820/etd.006464
Abstract
There is a lack of empirical or analytical evidence on how the combination of resilience strategies affects firm capabilities in the face of supply chain disruptions. In the first chapter, we use simulation modeling techniques to understand how different disruptions impact supply chain performance through direct and indirect interactions. We find various disruptions require different resilience strategies meaning there is no silver bullet strategy to deal with all disruptions. We also find that inventory and volume flexibility are strategies that combine well with others.The second chapter of this dissertation addresses two main questions. First, we examine the effect of three network structural characteristics on cascading disruptions. The quantile regression reveals that modularity and assortativity have heterogeneous effects on cascading disruptions across the conditional distributions of the outcome variables of interest. Second, we develop a new predictive model to identify the nexus suppliers whose disruptions would have a large impact on focal firms’ operations.
The final chapter develops new measures to operationalize the industrial and geographical concentrations of firms' upstream industries. The developed measures show that an industrial sector might be competitive and contain many suppliers (low industrial concentration) and yet be concentrated in a few nations or a small geographical area (high geographical concentration). Next, we document that the firms whose upstream suppliers are operating in highly concentrated industries on average experience 250 million US dollars reductions in sales. The proposed measures of industrial and geographical concentrations of firms' upstream industries are easy to compute and can help policymakers and managers systematically identify locations in supply networks that can create bottlenecks that may cause severe shortages or even threaten national security.
Details
- Title: Subtitle
- Essays on vulnerability of global supply chains
- Creators
- Jafar Namdar
- Contributors
- Jennifer Blackhurst (Advisor)Gautam Pant (Advisor)Kang Zhao (Committee Member)Sachin Modi (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Business Administration
- Date degree season
- Summer 2022
- DOI
- 10.25820/etd.006464
- Publisher
- University of Iowa
- Number of pages
- xi, 224 pages
- Copyright
- Copyright 2022 Jafar Namdar
- Language
- English
- Description illustrations
- illustrations (some color)
- Description bibliographic
- Includes bibliographical references (pages 195-224).
- Public Abstract (ETD)
A supply chain network includes a focal firm, which brings an identifiable product to the consumer market and its suppliers, which are spread across multiple tiers of the network. The suppliers, focal firms, and customers serve as nodes of the supply chain network. Within the supply chain network, disruptions can happen to cause an element of the supply chain to stop functioning, thus affecting the continuity of product flow. Disruptions like natural disasters (e.g., earthquakes, floods, hurricanes, pandemics like COVID 19) or man-made disasters highlight the importance of managing disruptions in the supply chain network. In the first chapter, we prescribe resilience or mitigation strategies that are most effective against different disruptions. We show various disruptions require different resilience strategies meaning there is no silver bullet strategy to deal with all disruptions. Also, combining resilience strategies is not always beneficial and can occasionally have detrimental effects.
In the second chapter, we propose a new predictive model that identifies the weakest node or supplier, aka the nexus supplier of the supply chain network. In fact, the nexus suppliers might cause huge cascade disruptions mainly due to their unique position in the supply network. The predictive model is evaluated on various real-world supply networks with thousands of nodes, and the model's performance is promising, with at least 90% accuracy in identifying nexus suppliers.
In the final chapter, we develop new measures to operationalize the industrial and geographical concentrations of firms' upstream industries. We show that competitive industries with ample suppliers may still impose significant risks on downstream firms if the industries are concentrated mainly in a few nations or small geographical areas. We document that the firms whose upstream suppliers are operating in highly concentrated industries on average experience 250 million US dollars reductions in sales.
- Academic Unit
- Tippie College of Business
- Record Identifier
- 9984285248802771
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