How does a business manage the flow of materials from supplier to customer, and how much stock should it hold?
Explain supply chain and inventory management, including supplier selection, stock control and just-in-time, and evaluate approaches to managing the supply chain
A focused answer to the H2 Management of Business outcome on supply chain and inventory. Supplier selection, stock control and buffer stock, just-in-time versus just-in-case, supply-chain resilience, and how to evaluate inventory and sourcing decisions.
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What this dot point is asking
SEAB wants you to explain how a business manages the flow of materials from supplier to customer and how much inventory to hold, and to evaluate the trade-offs. The central tension is between lean efficiency (minimal stock, low cost) and resilience (buffer stock, security against disruption) - and the exam rewards a selective answer that buffers the critical, vulnerable inputs rather than treating it as all-or-nothing.
The answer
The supply chain
The supply chain is the network through which materials flow from raw-material suppliers, through the firm's operations, to the final customer. Managing it well means getting the right inputs, in the right quantity and quality, at the right time and cost. Two big decisions dominate: who to source from (supplier selection) and how much stock to hold (inventory management).
Supplier selection
Choosing suppliers involves trading off price, quality, reliability, lead time, flexibility and ethics. A cheap supplier that is unreliable or low quality can be costly overall (stockouts, defects, reputational risk). Firms also choose between single sourcing (one supplier - simpler, possible discounts and close relationship, but vulnerable if it fails) and dual or multiple sourcing (more resilient and competitive, but more complex). Building strong supplier relationships and managing supplier risk are increasingly central.
Inventory (stock) management
Inventory includes raw materials, work-in-progress and finished goods. Holding stock has a clear trade-off:
- Costs of holding stock: capital tied up (opportunity cost), storage and insurance, and the risk of obsolescence, perishing or damage.
- Costs of holding too little: stockouts, lost sales, halted production, and lost customer goodwill.
Firms set a buffer (safety) stock - a minimum level held to protect against demand surges and supply delays - and a reorder level that triggers a new order, balancing these costs.
Just-in-time versus just-in-case
- Just-in-time (JIT) minimises stock by receiving inputs only as needed for production. It slashes holding costs and waste and frees up cash and space - but it relies on reliable, prompt suppliers and leaves little buffer, so a disruption can halt production.
- Just-in-case holds buffer stock to guard against disruption and surges. It is resilient but ties up capital and incurs holding costs.
Evaluating: lean versus resilient
JIT delivered huge efficiency gains, but supply shocks (pandemics, port and shipping disruption, geopolitical events) exposed the fragility of ultra-lean, single-sourced chains. The modern judgement is rarely "JIT or not" but how much resilience to build: selectively holding buffer stock and dual-sourcing for critical, single-sourced or hard-to-replace inputs, while keeping lean methods for stable, easily sourced items. The right balance depends on the cost and likelihood of disruption versus the cost of holding stock.
Examples in context
Example 1. Supply shocks and the rethink of JIT. Global disruptions - the pandemic, container-shipping bottlenecks, and chip shortages - halted production at many manufacturers whose ultra-lean, single-sourced supply chains had no buffer. The episode pushed firms to rebuild selective resilience: holding safety stock of critical components, dual-sourcing and "nearshoring", trading some lean efficiency for security. It is the clearest recent illustration of the lean-versus-resilient trade-off at the centre of this topic.
Example 2. Singapore as a supply-chain hub. Singapore's port and its role as a regional logistics and distribution hub make efficient inventory and supply-chain management central to many firms operating there, using its connectivity for fast replenishment and JIT-style supply. Yet firms also weigh resilience, holding regional buffer stock to serve Southeast Asia if a single route is disrupted - showing efficient flow and resilience being balanced in a trade-dependent location.
Try this
Q1. State two costs of holding high levels of inventory. [2 marks]
- Cue. Any two of: capital tied up in stock (opportunity cost); storage, warehousing and insurance costs; the risk of stock becoming obsolete, perishing or being damaged.
Q2. Explain one benefit and one risk of a just-in-time inventory system. [4 marks]
- Cue. A benefit is much lower stockholding cost and freed-up capital and space, because inputs arrive only as needed; a risk is fragility - with little or no buffer stock, any supplier delay or disruption can quickly halt production and cause lost output and orders. JIT trades efficiency for reduced resilience.
Q3. Analyse why a firm might choose dual sourcing despite the extra complexity. [6 marks]
- Cue. Dual sourcing - using two suppliers for the same input - protects against disruption: if one supplier fails, is delayed or raises prices, the firm can rely on the other, avoiding stockouts and production halts. It also keeps suppliers competitive on price and quality. The cost is greater complexity, smaller order discounts and more relationships to manage. For a critical, hard-to-replace input where a supply failure would be very costly, the resilience benefit outweighs the extra complexity; for a stable, easily sourced item, single sourcing may be simpler and cheaper - so the choice depends on the input's criticality and disruption risk.
Exam-style practice questions
Practice questions written in the style of SEAB exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Original8 marksA manufacturer using a just-in-time system suffered a costly production halt when a single overseas supplier was disrupted. Discuss whether it should move away from just-in-time toward holding more buffer stock.Show worked answer →
Define the systems. Just-in-time (JIT) minimises stock by receiving inputs only as needed, cutting holding costs and waste. Just-in-case holds buffer stock to protect against supply disruption and demand surges, at the cost of higher stockholding.
Apply to the case. The firm's JIT system left it with no buffer, so a single supplier disruption halted production - a costly failure of resilience. Holding more buffer stock would have cushioned the shock, keeping production running while the supply problem was resolved.
Analyse the trade-off. Moving toward buffer stock improves resilience and reduces the risk of stockouts and production halts, but raises stockholding costs (storage, capital tied up, obsolescence and waste risk) and partly sacrifices the lean efficiency JIT delivers. The firm need not abandon JIT entirely; it could hold buffer stock only for critical, single-sourced or hard-to-replace inputs, or dual-source to reduce dependence.
Evaluate with a judgement. A blanket return to high stock would be wasteful; the better response is targeted resilience - buffer stock and dual sourcing for the critical, vulnerable inputs that caused the halt, while keeping JIT for stable, easily sourced items. The right balance depends on the cost and likelihood of disruption versus the cost of holding stock. A strong answer rejects the binary, recommends selective resilience, and conditions it on input criticality and disruption risk.
Markers reward defining JIT versus just-in-case, analysing the resilience-versus-cost trade-off, and a judgement favouring selective buffering and dual sourcing for critical inputs rather than abandoning JIT.
Original6 marksExplain the purpose of holding buffer stock, and analyse one cost a business incurs by holding high levels of inventory.Show worked answer →
Explain buffer stock. Buffer (safety) stock is a minimum level of inventory held to protect against uncertainty - unexpected surges in demand or delays and disruptions in supply. It ensures the firm can keep producing or selling if deliveries are late or demand spikes, avoiding stockouts, lost sales and halted production.
Analyse one cost of high inventory. Holding high stock ties up working capital in unsold goods that could otherwise be used or invested (an opportunity cost), and incurs storage costs (warehousing, insurance, handling). There is also a risk of stock becoming obsolete, perishing or being damaged, especially for perishable or fast-changing products. So while buffer stock provides security, holding too much is costly.
Markers reward a clear purpose for buffer stock (protection against demand and supply uncertainty) and a developed cost of high inventory (capital tied up, storage, obsolescence).
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