Stock control — Edexcel A-Level Business
Test yourself on Stock control with PEARSON EDEXCEL A-Level practice questions.
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Stock control explained
The chart plots stock on the vertical axis against time on the horizontal one, and it repeats a sawtooth: stock falls as it is used, a delivery arrives and the line jumps back to the maximum level.
Read the full explanation
Four lines carry the marks. The maximum shows what the warehouse can hold or the firm is willing to fund, the re-order level is the point at which an order is placed, the buffer or minimum sits underneath as the cushion, and the lead time is the horizontal gap between placing the order and the delivery arriving. The gradient of the falling line is the usage rate, so a steeper slope means faster consumption and forces a higher re-order level. Most questions ask you to read an unusual event off the chart, a late delivery eating into the buffer, a demand spike, or a stock-out where the line touches zero.
b) Buffer stocks
This is the deliberate cushion, the minimum level a firm aims never to dip below, held so that a late lorry or a sudden rush of orders does not halt production or empty the shelf. Sizing it is a judgement about risk against cost. The wider the swing in weekly demand, the longer and less reliable the supplier's lead time, and the more damaging a stock-out would be, the bigger the cushion should be; against that sit storage and insurance costs, the risk of obsolescence in fashion or electronics, spoilage in food, and the cash locked up that could have paid down debt. The semiconductor shortage that stopped car assembly lines in twenty twenty one pushed many manufacturers to rebuild cushions they had spent decades stripping out, which is the practical counterweight to just in time thinking.
c) Implications of poor stock control
The damage runs in both directions. Hold too much and cash that could have funded growth or paid suppliers sits in the warehouse, storage, handling and insurance costs mount, and goods are marked down, spoil or go out of fashion before they sell. Hold too little and the line stops while staff are still paid, orders are turned away, emergency deliveries are bought at premium freight rates, and customers who could not get what they wanted try a competitor and may not come back. The usual measure is inventory turnover, cost of sales divided by average inventory, giving the number of times stock is sold and replaced in a year; divide three hundred and sixty five by it for days of stock held. Rising days of stock with flat sales is the warning sign a case study normally plants.
d) Just in time (JIT) management of stock
Under this approach components arrive from suppliers only as the line needs them, so stock is close to zero and production is pulled by actual orders rather than pushed by a forecast. Toyota built the method, and it only works with frequent small deliveries, suppliers close by and trusted, quality right first time because there is no spare part to swap in, flexible multi-skilled staff and good information systems. The prize is large: working capital released from the warehouse, lower storage and insurance costs, far less obsolete stock, and problems exposed rather than hidden behind a pile of spares. The exposure is equally large, since one strike, port delay or supplier failure stops everything, bulk discounts are lost, and more frequent deliveries raise transport costs and emissions.
e) Waste minimisation
Lean thinking treats anything the customer would not pay for as waste, which covers overproduction, waiting time, unnecessary movement of goods and people, over-processing, excess inventory and defects, alongside scrapped material and wasted energy. The tools are practical: kaizen and continuous improvement suggestions from the people doing the job, cell production, quality assurance so faults are prevented rather than inspected out at the end, and total quality management. The pay-off is a lower unit cost, fewer costly reworks and a sustainability story customers and investors now expect, as supermarkets have found with food waste targets. The catch is that it takes training, time and investment before savings appear, and staff resist enthusiastically if efficiency drives look like a route to job cuts.
f) Competitive advantage from lean production
Lean means running the operation with the least input for a given output, so waste in stock, waiting, movement and defects is stripped out using just in time delivery, cell production, kaizen and time based management. In a decision it is the route to a lower unit cost, which supports either a cost leadership position in Porter's generic strategies or a wider margin at the existing price. It also frees the cash tied up in inventory and shortens lead times, which is a selling point in itself. The trade off is fragility, because with almost no buffer stock a supplier failure, a strike or a port delay stops the line, as the semiconductor shortage did to car assembly plants. Lean also depends on trained, flexible, motivated staff, so a firm with high labour turnover or adversarial suppliers rarely collects the promised saving.
Your focus
- a) Interpretation of stock control diagram
- b) Buffer stocks
- c) Implications of poor stock control
Show all 6 objectives
- d) Just in time (JIT) management of stock
- e) Waste minimisation
- f) Competitive advantage from lean production
Stock control exam tips
Marking Points
- Names the features correctly from the chart, maximum stock level, re-order level, buffer or minimum stock, lead time and re-order quantity
- Reads the usage rate off the gradient and expresses it in units per day or per week using the axes given
- Explains an irregularity in terms of a business cause, for example a shallower slope shows demand falling while a delay before the vertical jump shows a supplier missing the lead time
- Uses the chart to make a recommendation, such as raising the buffer because the lead time has proved unreliable, and notes the working capital that ties up
- Defines it as the minimum stock held as protection against late delivery or unexpected demand, not simply as leftover stock
- Identifies what should determine its size for this firm, demand variability, lead time reliability, shelf life and the cost of a lost sale
- Costs the decision both ways, naming storage, insurance, obsolescence and tied up working capital against lost orders, idle labour and reputational damage
- Applies to the product in the case, since a buffer of fresh fish is a different proposition from a buffer of steel fixings
- Deals with both failures, overstocking and understocking, rather than only the shortage side
- Links overstocking to cash flow specifically, money tied up in inventory is unavailable to pay suppliers or wages, which can push a profitable firm into a liquidity problem
- Traces understocking through to the customer, lost orders, longer lead times, damaged reputation and a rival gaining the sale
- Supports the argument with the inventory turnover calculation or days of stock where the case provides cost of sales and inventory figures
- Identifies a plausible underlying cause such as weak demand forecasting, poor supplier relationships or outdated recording systems, then suggests a proportionate fix
- Describes the system accurately as stock arriving as it is needed with minimal buffer, and identifies it as a pull system driven by orders
- States the conditions it depends on, reliable nearby suppliers, close long term relationships, quality at source, flexible workers and accurate ordering systems
- Quantifies the benefit where possible, converting warehouse space saved or average stock reduced into a cash or cost figure for the business
- Sets the risk against the saving, naming supply disruption, loss of bulk discounts and higher delivery costs, and judges whether the firm's supply chain is robust enough
- Identifies waste broadly rather than as scrap alone, including waiting, overproduction, excess stock, unnecessary movement and defects
- Names a specific technique, kaizen, cell production, quality at source or total quality management, and explains how it removes that waste in the business described
- Links the reduction to a financial outcome, lower material and rework cost per unit, which protects margin or allows a more competitive price
- Recognises the wider benefit for reputation and compliance with environmental targets, and the cost of achieving it in training and disruption
- Judges realistically whether this firm has the culture, time and cash to make continuous improvement stick
- Define lean in a clause and then name the specific technique the case business uses, such as just in time ordering or kaizen teams, rather than listing every lean tool.
- Convert the saving into a number the marker can see: lower inventory holding cost, higher inventory turnover, better capacity utilisation, or a lower unit cost per item.
- Link the cost saving explicitly to the chosen strategy, so a lower unit cost becomes either a lower price to win share or a fatter margin at the existing price.
- Judge whether the advantage lasts, since lean methods can be copied and the durable part usually sits in supplier relationships and workforce skill that rivals cannot buy quickly.
Examiner Tips
- 💡Diagram questions are typically short, two to four marks, and are marked on precision, so use the specification's own labels and quote figures straight from the axes
- 💡If the chart shows a stock-out, follow it through to lost sales, idle staff and the customer going to a rival, since that is where the analysis marks sit
- 💡Expect a follow up asking whether the buffer should change, which needs the cost of holding stock set against the cost of running out
- 💡The usual question asks you to assess whether a named business should increase its buffer, so build the answer around the cost of holding stock against the cost of a stock-out
- 💡Bring in working capital and the cash flow forecast if the case shows the firm is short of cash, because that often decides the judgement
- 💡Use the industry to qualify your conclusion, as perishability, seasonality and supplier distance all change the right answer
- 💡Look for the cash flow forecast or balance sheet in the evidence, since inventory usually appears there and the examiner expects you to use the figure
- 💡Analyse questions want one developed chain, so choose either the cash consequence or the customer consequence and follow it right through to profit
- 💡In evaluation, weigh the cost of better systems, training and stock software against the savings, because small firms often cannot justify the investment
- 💡The common evaluation question asks whether a named firm should move to this system or back towards holding more stock, so structure the answer as a comparison and judge on supply chain reliability
- 💡Bring in recent disruption evidence such as pandemic shipping delays or component shortages, briefly, as support for the counter argument
- 💡Connect it to lean production and waste minimisation, because examiners reward answers that show the operations topics working together
- 💡Expect it inside a wider question on competitiveness or profitability, so always end with the effect on unit cost, margin or reputation rather than stopping at the technique
- 💡Use motivation theory, particularly Herzberg on responsibility and recognition, to explain why involving employees in improvement works better than imposing targets, and note that it says little about pay in a low wage workplace
- 💡Give one brief real example, such as a retailer cutting food waste, and keep it to a clause so the marks go on the analysis
- 💡This is usually the lever in a longer question on how a named manufacturer defends its margin, so plan two developed arguments and a supported judgement rather than four thin ones.
- 💡The data response often prints inventory figures, so work out inventory turnover or stock holding cost first and quote the result inside the argument.
- 💡Where the command word is assess or evaluate, hang the judgement on a condition such as supplier reliability, demand stability or order size.
Common Mistakes
- Confusing the re-order level with the buffer stock; the re-order level is the trigger to place an order and sits above the buffer, which is only touched when something goes wrong
- Misreading lead time as the time between deliveries, when it is the interval between placing the order and receiving it
- Reading values off the axis without units, so an answer says the business holds four hundred without saying whether that is units, kilograms or days of cover
- Assuming a bigger buffer is always safer, which ignores the cash it swallows and the write-offs when perishable or fashionable stock does not sell
- Treating buffer stock as incompatible with all lean thinking, when many just in time firms still hold a small cushion of critical components with unreliable suppliers
- Describing the benefit only as avoiding running out, without naming the consequence avoided, such as an idle production line still paying wages
- Writing only about waste and forgetting that excess stock is primarily a cash flow problem, which is where the strongest marks are
- Calculating inventory turnover with revenue instead of cost of sales, which inflates the figure and makes the comparison with a rival meaningless
- Assuming the highest possible turnover is best, when very fast turnover with no cushion leaves a business one late delivery away from a stock-out
- Claiming it removes all stock, when most firms keep a small cushion of critical or long lead time components
- Listing benefits without applying them, so the answer never says what this particular business would do with the cash released or the space freed
- Ignoring the supplier side, since the method only shifts the holding cost onto suppliers unless the relationship and the ordering information are genuinely shared
- Treating it as purely an environmental or recycling issue and never reaching the cost per unit and profit consequences the question is really about
- Assuming continuous improvement is free, when it needs training, meeting time, measurement and often new equipment before any saving is banked
- Overlooking employee resistance, since improvement schemes that are seen as a prelude to redundancies produce few suggestions and poor engagement
- Treating lean as a synonym for sacking staff or buying cheaper materials, when lean removes waste from the process and cutting people often raises defects and rework.
- Claiming just in time always reduces cost while ignoring the higher ordering and delivery costs of frequent small deliveries.
- Asserting a competitive advantage without saying who the rivals are or what customers actually value, so the answer never reaches evaluation.