📚 Year 8 WJEC Economics: Case Study Practical Drill | 八年级 WJEC 经济：案例分析实战演练
Welcome to your hands‑on case study practice for Year 8 WJEC Economics. In this revision article we will work through realistic micro‑economic scenarios that help you sharpen the skills of identifying economic concepts, applying demand and supply, interpreting data and making reasoned judgements. Each case is designed around WJEC assessment objectives so you can build confidence ahead of your topic tests or end‑of‑year exam.
欢迎来到八年级 WJEC 经济学的案例分析实战演练。在这篇复习文章中，我们将一起完成若干个贴近现实的微观经济情境，帮助你磨练识别经济概念、运用需求与供给、解读数据以及做出有理有据判断的能力。每一个案例都紧扣 WJEC 考试目标，让你在单元测验或年终考试前建立起充足信心。
1. What Is a Case Study in Economics? | 什么是经济案例分析？
In WJEC Year 8 Economics, a case study is a short description of a real‑world or imagined situation that involves an economic problem. Your task is to read the background carefully, pull out the main economic ideas, and then use simple models—such as supply and demand, costs and benefits—to explain what is happening and suggest possible solutions. Think of yourself as an economic detective: you gather clues from the text, connect them to theory, and draw conclusions that are supported by evidence.
在 WJEC 八年级经济学中，案例分析就是一段对真实或虚构情境的简短描述，其中包含一个经济问题。你的任务是仔细阅读背景信息，提炼出主要的经济概念，然后运用简单的模型——例如供需关系、成本与收益——来解释正在发生的事情，并提出可能的解决方案。把自己想象成一名经济侦探：你从文字中收集线索，将线索与理论联系起来，然后得出有证据支持的结论。
Case studies are not just about getting the ‘right’ answer. They test your ability to apply knowledge, weigh up different factors, and communicate economic reasoning clearly. In the WJEC exam, you might be asked to identify causes of a price change, explain how a business can improve its profits, or evaluate a government policy. The more you practise, the quicker you become at spotting which concept to use.
案例分析并不只是追求“正确”答案。它们考验你运用知识、权衡不同因素以及清晰表达经济推理的能力。在 WJEC 考试中，你可能会被要求找出价格变动的原因，解释企业如何提高利润，或者评价一项政府政策。练习得越多，你在判断该使用哪个概念时就会越快、越准。
2. The Four‑Step Drill for Any Case | 案例四步分析法
Before we dive into the scenarios, let's agree on a simple framework that will structure your analysis every time. I call it the 'D.A.T.E.' approach: Describe, Apply, Test, Evaluate.
在我们深入具体情境之前，先约定一个简单框架，它能帮助你每次分析时都条理清晰。我称之为“D.A.T.E.”四步法：描述（Describe）、应用（Apply）、检验（Test）、评估（Evaluate）。
Step 1 – Describe the economic problem: In your own words, say what decision needs to be made or what change is being observed. Is it a business trying to set the best price? A government wanting to reduce litter? A worker choosing whether to work extra hours? Be precise.
第一步——描述经济问题：用自己的话说出需要做出的决定，或者正在被观察到的变化。是一家企业想制定最优价格？是政府想减少垃圾？还是一名劳动者在选择是否加班？表述要准确。
Step 2 – Apply relevant economic concepts: Link the problem to the theory you have learned. Maybe the case shows a shift in demand (like a hot summer increasing ice cream sales) or mentions fixed and variable costs. Draw a quick sketch of a supply and demand diagram in your head or on paper, labelling the axes price and quantity. Note down which curve shifts and which way.
第二步——应用相关经济概念：把问题和学过的理论联系起来。也许案例展示了需求的变动（如炎热的夏天让冰淇淋销量上升），也许提到了固定成本和可变成本。在脑海中或纸上快速画一幅供需图，标好价格轴和数量轴。记下哪条曲线发生了移动，以及向哪个方向移动。
Step 3 – Test with data from the case: Look back at any numbers, percentages or facts given. Do they support your first idea? If a bakery’s sales dropped 15% when it raised prices, what does that tell you about price elasticity of demand? Use the figures to back up your claim.
第三步——用案例数据检验：回头查看给定的任何数字、百分比或事实。它们支持你的初步想法吗？如果一家烘焙店提价后销量下降了15%，这告诉你关于需求价格弹性的什么信息？用数据来支撑你的观点。
Step 4 – Evaluate and suggest: No economic decision is perfect. Think about the short‑run versus long‑run, who might win or lose, and what could go wrong. Then give a balanced conclusion. For example, raising the price might increase revenue now but damage reputation later.
第四步——评估并给出建议：没有哪个经济决策是完美的。考虑短期与长期、谁会受益或受损，以及哪些地方可能出错。然后给出一个平衡的结论。例如，涨价现在能增加收入，但日后可能损害声誉。
3. Practical Case 1: The Lilac Lane Bakery’s Pricing Decision | 实战案例 1：丁香巷烘焙店的价格决策
Read the following information carefully. A local bakery, Lilac Lane, has been selling its signature chocolate chip cookies at £1.50 each for the past year. In the last three months, a new coffee shop opened two streets away, selling similar cookies for £1.20. Lilac Lane’s owner notices that weekly cookie sales have fallen from 400 to 340 units. The owner also knows that ingredient costs have risen by 10% and is thinking about raising the cookie price to £1.70. However, a customer survey revealed that 60% of buyers would switch to the coffee shop if the price went above £1.50.
请仔细阅读以下信息。本地一家名为“丁香巷”的烘焙店，过去一年一直以每块 1.50 英镑的价格销售其招牌巧克力碎曲奇。在过去三个月里，两条街外新开了一家咖啡店，出售类似曲奇，售价 1.20 英镑。丁香巷的店主注意到每周曲奇销量从 400 块下降到了 340 块。店主还了解到原材料成本上涨了 10%，因此正考虑将曲奇价格提高到 1.70 英镑。然而，一项顾客调查显示，如果价格超过 1.50 英镑，60% 的买家会转向那家咖啡店。
Your tasks:
1. Identify two economic concepts shown in this case.
2. Calculate the percentage change in weekly sales.
3. Explain, using demand and supply, what would likely happen if the price is raised to £1.70.
4. Make a recommendation to the owner and justify it.
你的任务：
1. 找出本案例中体现的两个经济概念。
2. 计算每周销量的百分比变化。
3. 运用需求与供给，解释如果价格提高到 1.70 英镑可能会发生什么。
4. 向店主提出建议并说明理由。
4. Analysis of Case 1: Competition, Elasticity and Revenue | 案例 1 分析：竞争、弹性与收入
Let’s work through the case step by step using our D.A.T.E. method. First, describe: The bakery faces a competitor selling at a lower price, leading to a drop in quantity sold. At the same time, costs are rising. The problem is whether to raise price to cover costs without losing too many customers.
让我们用 D.A.T.E. 方法逐步分析这个案例。第一步，描述：烘焙店面临售价更低的竞争者，导致销量下降。与此同时，成本在上升。问题是该不该提价以覆盖成本，同时不至于流失太多顾客。
Apply concepts: The economic ideas here include substitute goods (the coffee shop’s cookies are a close substitute) and price elasticity of demand. Because a significant number of customers are willing to switch, demand for Lilac Lane’s cookies appears to be elastic—a price rise would cause a proportionally larger fall in quantity demanded. We can also see the effect of a shift in the supply curve: higher ingredient costs shift supply leftwards, putting upward pressure on price.
应用概念：这里涉及的经济学概念包括替代品（那家咖啡店的曲奇就是接近的替代品）和需求价格弹性。由于相当多的顾客愿意转向竞争者，丁香巷曲奇的需求似乎是有弹性的——价格上升会导致需求量更大幅度的下降。我们也能看到供给曲线移动的影响：原材料成本上升使供给曲线左移，给价格带来上行压力。
Test with data: Percentage fall in sales = (400 − 340) ÷ 400 × 100 = 15%. If the price were raised from £1.50 to £1.70, that’s a 13.3% increase ((0.20 ÷ 1.50)×100). With 60% of customers ready to switch, the quantity demanded could fall by far more than 13.3% uantity) would likely drop. Elastic demand and strong substitutes make a price hike risky.
检验数据：销量下降百分比 = (400 − 340) ÷ 400 × 100 = 15%。如果把价格从 1.50 英镑提高到 1.70 英镑，涨幅为 13.3%（(0.20 ÷ 1.50)×100）。考虑到 60% 的顾客准备转向竞争者，需求量的下降幅度很可能远超 13.3%，这意味着收入（价格 × 数量）极有可能减少。富有弹性的需求和强大的替代品使得提价风险很大。
Evaluate: Raising prices might increase the margin per cookie, but total revenue could fall because of the sharp drop in sales. In the long run, loyal customers may also leave if they feel they are being overcharged. One option could be to differentiate the product—maybe offer a loyalty card or a slightly larger cookie—so that customers see it as less substitutable. Alternatively, the bakery could absorb some of the cost increase and focus on selling high‑margin drinks alongside cookies. A balanced recommendation: do not raise price to £1.70; instead, keep the price at £1.50, highlight the quality, and introduce a small coffee‑and‑cookie deal to win back market share.
评估：提价或许能提高每块曲奇的利润，但由于销量大幅下跌，总收入可能会减少。从长远看，如果忠实顾客觉得被多收了钱，他们也可能离开。一个办法是使产品差异化——比如推出积分卡或提供稍大块的曲奇——让顾客觉得它不那么容易被替代。另一个选择是消化部分成本上涨，同时专注于销售利润较高的饮品搭配。一个平衡的建议是：不要把价格提到 1.70 英镑；相反，保持 1.50 英镑的售价，突出品质，并推出小额咖啡加曲奇套餐，以赢回市场份额。
5. Practical Case 2: A Tax on Single‑Use Plastic Bags | 实战案例 2：对一次性塑料袋征税
The government of a small country has noticed a sharp increase in plastic waste, especially single‑use shopping bags, which clog rivers and harm wildlife. At present, 50 million bags are used each month, and consumers receive them for free at supermarkets. The government proposes a tax of 5p per bag, which would be added at the checkout. A similar policy in a neighbouring country led to a 70% reduction in bag use within six months. However, some shop owners argue the tax will annoy customers and cost jobs in the plastic‑bag manufacturing industry.
一个小国的政府注意到塑料垃圾急剧增加，尤其是一次性购物袋，它们堵塞河流并危害野生动植物。目前，每月消耗 5000 万个塑料袋，消费者在超市免费领取。政府提议每个塑料袋征收 5 便士的税，在收银台叠加收取。邻国实施类似政策后，六个月内塑料袋使用量减少了 70%。然而，一些店主认为这项税收会惹恼顾客，并导致塑料袋制造业流失工作岗位。
Your tasks:
1. What is the economic term for the harm caused by plastic bags?
2. Explain how a 5p tax shifts the supply curve for plastic bags.
3. Discuss one cost and one benefit of the policy.
4. Based on evidence from the neighbouring country, predict the change in monthly bag usage if the tax is introduced, and calculate the expected new quantity.
你的任务：
1. 塑料袋造成的危害在经济学术语中叫什么？
2. 解释 5 便士的税如何移动塑料袋的供给曲线。
3. 讨论该政策的一个成本和一个收益。
4. 根据邻国的证据，预测如果引入该税，每月塑料袋使用量的变化，并计算预期的新的使用量。
6. Analysis of Case 2: Externalities and Government Intervention | 案例 2 分析：外部性与政府干预
Describe the problem: The overuse of plastic bags creates a negative externality—costs to third parties (wildlife, clean‑up crews) that are not reflected in the market price of zero. This is a classic case of market failure where too many bags are consumed because consumers do not bear the full social cost.
描述问题：塑料袋的过度使用产生负外部性——给第三方（野生动植物、清洁人员）带来成本，而这些成本并未反映在零市场价格中。这是一个典型的市场失灵例子：由于消费者没有承担全部社会成本，塑料袋被过度消费。
Apply: A tax of 5p per bag internalises the externality. In supply‑and‑ um price faced by consumers rises (from free to 5p), and the equilibrium quantity falls. Diagrammatically: initial supply S₀, demand D, equilibrium at (Q=50m, P=0). After tax, supply shifts to S₁ = S₀ + 5p, new equilibrium at a lower quantity.
应用：每个塑料袋 5 便士的税收将外部性内部化。从供需角度看，税收相当于增加了生产成本，使供给曲线向上垂直移动税收金额的量。消费者面对的新均衡价格上升（从免费变为 5 便士），均衡数量下降。图中表示为：初始供给 S₀，需求 D，均衡点为（Q=5000万，P=0）。征税后，供给移动到 S₁ = S₀ + 5 便士，新的均衡数量降低。
Test: The neighbouring country saw a 70% reduction. Applying that to 50 million bags: 70% month. This assumes similar consumer behaviour and availability of substitutes like reusable bags.
检验：邻国实现了 70% 的降幅。将该比例应用于 5000 万个塑料袋：70% × 50,000,000 = 35,000,000 个减少量，因此新的使用量约为每月 1500 万个。这假设了类似的消费者行为，并且有可重复使用袋子等替代品可获取。
Evaluate: Benefits include a cleaner environment, lower waste‑management costs, and a possible increase in reusable‑bag production jobs. Costs might involve initial inconvenience for shoppers, a slight rise in shopping bills for those who forget reusable bags, and job losses in the plastic‑bag sector. However, the experience of the neighbouring country suggests the net benefit is strongly positive. Governments could also use the tax revenue to fund environmental projects, strengthening the policy’s positive impact.
评估：收益包括更清洁的环境、更低的垃圾管理成本，以及可重复使用袋子生产岗位的可能增加。成本可能涉及消费者初期的不便、忘记带购物袋的人购物支出略微上升，以及塑料袋行业的失业。但邻国的经验表明，净收益是强烈正向的。政府还可以将税收收入用于资助环保项目，进一步增强政策的积极影响。
7. Practical Case 3: ByteStart – A Tech Start‑Up’s Hiring Decision | 实战案例 3：ByteStart——一家科技初创公司的招聘决策
ByteStart is a small software company that has just won a contract to deliver an app project in three months. Currently, it employs two programmers who together can produce 20 units of work per week. The owner is considering hiring a third programmer for a monthly salary of £2,800. The third worker would increase total weekly output to 28 units, according to a trial period. A fourth worker was tested but only added 4 more units, taking total output to 32. Each unit of work earns the firm £200 in revenue.
ByteStart 是一家小型软件公司，刚刚赢得了一份在三个月内交付应用项目的合同。目前，公司雇有两名程序员，他们每周一共可以产出 20 个工作单元。公司老板正在考虑以每月 2800 英镑的薪水聘请第三名程序员。根据试用期表现，第三名员工将使每周总产出增加到 28 个工作单元。第四名员工也经过测试，但只增加了 4 个工作单元，使总产出达到 32。每个工作单元可为公司带来 200 英镑的收入。
Your tasks:
1. Calculate the marginal product of the third worker and of the fourth worker.
2. Work out the marginal revenue product (MRP) of the third worker per week (assume 4 weeks in a month for simplicity).
3. Should ByteStart hire the third programmer? Explain using MRP and wage cost.
4. What economic law is illustrated by the falling extra output of the fourth worker?
你的任务：
1. 计算第三名员工的边际产量和第四名员工的边际产量。
2. 计算第三名员工每周的边际收益产品（MRP）（为简化，假设一个月有 4 周）。
3. ByteStart 是否应该聘请第三名程序员？运用 MRP 和工资成本进行解释。
4. 第四名员工新增产出下降说明了什么经济定律？
8. Analysis of Case 3: Marginal Thinking and Diminishing Returns | 案例 3 分析：边际思维与边际收益递减
Describe: ByteStart must decide whether to expand its workforce based on the additional revenue each new worker brings in, compared to the extra cost. This is a textbook application of marginal analysis.
描述：ByteStart 必须根据每名新员工带来的额外收入与额外成本的比较，来决定是否扩大团队。这是边际分析的一个教科书式应用。
Apply key concepts: Marginal product (MP) orker. MP of the 3rd worker = 28 − 20 = 8 units. MP of the 4th worker = 32 − 28 = 4 units. Marginal revenue product (MRP) = MP × price per unit. For the 3rd worker, weekly MRP = 8 × £200 = £1,600. The weekly wage cost = £2,800 ÷ 4 = £700. Since MRP (£1,600) > wage (£700), hiring the third worker adds £900 to weekly profit, so the firm should hire.
应用关键概念：边际产量（MP）是指增加一名工人所带来的额外产出。第三名工人的 MP = 28 − 20 = 8 个工作单元。第四名工人的 MP = 32 − 28 = 4 个工作单元。边际收益产品（MRP）= MP × 单位价格。对第三名工人而言，每周 MRP = 8 × 200 英镑 = 1600 英镑。每周工资成本 = 2800 英镑 ÷ 4 = 700 英镑。由于 MRP（1600 英镑）大于工资（700 英镑），聘用第三名工人会使每周利润增加 900 英镑，因此公司应该聘请。
Test the numbers: The fourth worker gives MRP of 4 × £200 = £800, still slightly above the weekly wage of £700 but only by £ are certain about the contract’s workload, but the gain is much smaller and highlights the law of diminishing returns: as more variable factors (labour) are added to a fixed factor (office space, equipment), the extra output per worker eventually falls.
检验数据：第四名工人的 MRP = 4 × 200 英镑 = 800 英镑，仍然略高于每周 700 英镑的工资，但只高出 100 英镑。如果公司对合同工作量很有把握，或许仍会考虑聘用第四人，但收益已大大缩小，并突显了边际收益递减规律：当可变要素（劳动力）不断增加并投入固定要素（办公空间、设备）时，每名工人的额外产出最终会下降。
Evaluate: The third hire is a clear ‘yes’ because it significantly boosts profit. For the fourth, management should think about whether the current fixed resources can support four programmers efficiently without creating congestion or communication delays. They could also explore alternative strategies, such as paying overtime to existing staff rather than committing to a new salary. Marginal analysis always helps us focus on the additional benefits versus additional costs, avoiding the trap of thinking ‘more is always better’.
评估：聘用第三人显然应该同意，因为这会显著提升利润。至于第四人，管理层需要考虑当前的固定资源能否在不造成拥挤或沟通延迟的情况下高效支持四名程序员。他们还可以探索其他策略，例如给现有员工支付加班费，而不是承担一份新的薪水。边际分析总是帮助我们聚焦于额外的收益与额外的成本，避免陷入“越多越好”的思维陷阱。
9. Common Mistakes and a Quick Checklist | 常见错误与快速检查清单
Even strong students can lose marks in case study questions by making small but important errors. Let’s review the most frequent pitfalls and then use a checklist to keep you on track.
即使是优秀的学生，也可能因为一些细小却关键的错误而在案例分析题中失分。我们来看看最常出现的陷阱，然后用一份检查清单确保你走在正轨上。
Mistake 1: Confusing a shift of the demand curve with a movement along it. A price change of the good itself causes a movement along the demand curve; a change in income, tastes or the price of a substitute shifts the whole curve. Always ask: ‘Has the price of this product changed, or has something external affected people’s desire to buy it?’
错误一：混淆需求曲线的移动与沿着需求曲线的移动。商品自身价格的变动导致沿着需求曲线的移动；而收入、偏好或替代品价格的变化会引起整条曲线的位移。始终要问：“是这个产品自身的价格变了，还是外部因素影响了人们的购买意愿？”
Mistake 2: Ignoring data. Many case studies provide figures deliberately. If you are told a tax of 10% reduced consumption by 5%, use those numbers to calculate and comment on elasticity. Quotes like ‘sales rose by 20 units’ should be included in your written answer.
错误二：忽视数据。很多案例会故意提供数据。如果题干说某项 10% 的税使消费量减少了 5%，就应当用这些数字去计算并评论弹性。像“销量增加了 20 个单位”这类信息务必写进你的文字答案中。
Mistake 3: Unrealistic recommendations. A suggestion like ‘close the business’ is rarely the best answer for a case about a small price dip. Always balance short‑run and long‑run effects, and consider who the stakeholders are—owners, workers, customers, the government.
错误三：不切实际的建议。对于一个面临小幅降价的案例，“关掉企业”很少是最佳答案。要始终兼顾短期和长期影响，并考虑利益相关者是谁——业主、工人、顾客、政府。
Below is a handy checklist you can run through after writing your response.
下方是一份方便的检查清单，写完答案后你可以逐项核对。
| Checklist Item | Checked? (√) |
|---|---|
| Did I identify at least two economic concepts by name? | |
| Did I use a diagram (even a mental one) to show shifts or movements? | |
| Did I back up every argument with data from the case? | |
| Did I calculate percentage changes or values where possible? | |
| Did I mention the time dimension (short run vs long run)? | |
| Did I consider who wins and who loses? | |
| Did I end with a balanced judgement or recommendation? |
10. Conclusion: Drill, Review, Succeed | 结论：反复演练，回顾，直至成功
Case studies might look intimidating at first, but they are simply puzzles built from the economic concepts you already know. By following the D.A.T.E. structure—Describe, Apply, Test, Evaluate—and practising with real‑life scenarios like bakery pricing, plastic bag taxes and hiring decisions, you train your brain to think like an economist. Remember that WJEC examiners are looking for application, not just description. Use the vocabulary: substitute, elasticity, externality, marginal product, revenue, and so on, but always in context.
案例分析乍一看可能令人生畏，但它们不过是用你已然掌握的经济概念搭建的拼图。通过遵循 D.A.T.E. 框架——描述、应用、检验、评估，并借助烘焙店定价、塑料袋税和招聘决策等真实情境反复练习，你将训练自己的大脑像经济学家一样思考。记住，WJEC 考官看重的是知识的应用，而不仅仅是描述。大胆使用这些术语：替代品、弹性、外部性、边际产量、收入等等，但一定要结合上下文。
The key to mastery is consistency. Every time you complete a practice case, compare your answer with the four‑step model, check the common mistakes list, and note one thing you would improve. Over time, you will find yourself spotting economic problems faster, calculating impacts with confidence, and writing evaluations that
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