📚 IGCSE WJEC Economics: A Practical Guide to Economic Investigations | IGCSE WJEC 经济：实验操作指南
Economic investigations give you a hands-on way to explore how people and markets behave. For WJEC IGCSE Economics students, learning to design and run simple experiments or surveys bridges the gap between theory and real-world decision-making, sharpening your analytical skills for the exam and beyond.
经济调查为你提供了一种亲身探究人类与市场行为的方式。对于 WJEC IGCSE 经济学学生而言，学习设计和开展简单的实验或问卷调查，能够弥合理论与现实决策之间的鸿沟，并提升你的分析能力，以应对考试及未来的需求。
1. Understanding Economic Experiments | 理解经济实验
An economic experiment is a controlled setup where participants make choices involving incentives, scarcity, or trade-offs. Unlike natural science labs, these experiments often use hypothetical scenarios or token rewards to observe behaviour such as bidding, bargaining, or responding to policy changes.
经济实验是一种受控的设置，参与者在其中做出涉及激励、稀缺性或权衡取舍的选择。与自然科学的实验室不同，这类实验通常使用假设情景或代币奖励，来观察参与者的行为，例如竞标、讨价还价或对政策变化的反应。
You can run experiments in a classroom by assigning roles like buyers and sellers, and giving them budget constraints. The goal is to test economic theories, such as the law of demand, or to see how information affects market outcomes.
你可以在教室中通过分配买方和卖方等角色，并给予他们预算约束，来进行实验。其目的是检验经济理论（例如需求定律），或观察信息如何影响市场结果。
2. Identifying a Research Question | 明确研究问题
Every investigation starts with a clear, focused question. Instead of a vague topic like ‘market prices’, narrow it down to ‘How does the number of sellers affect the equilibrium price in a classroom double-auction market?’ A good research question is specific, measurable, and linked to an economic concept.
每一次调查都始于一个清晰、聚焦的问题。与其用“市场价格”这样模糊的话题，不如将其缩小为“在课堂双向拍卖市场中，卖方数量如何影响均衡价格？”一个好的研究问题是具体、可测量且与经济学概念相关联的。
Use the ‘why’ and ‘what if’ prompts to generate ideas. For WJEC exams, you might be asked to design an investigation on price elasticity, the impact of a subsidy, or factors influencing saving behaviour. Always check that your question can be answered with the data you can realistically collect.
使用“为什么”和“如果……会怎样”的提示来激发想法。在 WJEC 考试中，你可能被要求设计关于价格弹性、补贴影响或影响储蓄行为因素的调查。务必核实你的问题能够用你能实际收集到的数据来回答。
3. Choosing an Experimental Design | 选择实验设计
Select between a laboratory-style experiment (in a controlled classroom setting), a field experiment (in a natural environment like the school canteen), or a survey-based design. Classroom markets, for instance, allow you to control variables such as endowments and trading rules.
选择实验室式实验（在受控的教室环境中）、实地实验（在学校食堂等自然环境中）或基于问卷的设计。例如，课堂市场允许你控制初始禀赋和交易规则等变量。
A between-subjects design compares different groups (e.g., one group with perfect information, another with limited information) to isolate the effect of a variable. A within-subjects design lets the same participants experience different conditions in sequence, reducing individual differences but risking order effects.
组间设计比较不同群体（例如，一组拥有完全信息，另一组信息有限），以隔离某个变量的影响。组内设计则让相同的参与者依次体验不同条件，减少了个人差异，但存在顺序效应的风险。
4. Recruiting Participants and Ethics | 招募参与者与伦理规范
For classroom investigations, your classmates become the subject pool. Ensure you obtain their informed consent: explain the procedure, that participation is voluntary, and that data will be anonymised. Avoid any deception that might cause harm or distress, and never use real money without permission.
对于课堂调查而言，你的同学就是被试群体。确保获得他们的知情同意：解释流程、说明参与是自愿的，并且数据将匿名化处理。避免任何可能造成伤害或困扰的欺骗行为，未经允许不得使用真实货币。
Ethical guidelines align with WJEC’s emphasis on responsible research. If you are recording choices, use codes instead of names. When studying sensitive topics like income or spending habits, let participants skip questions. Debrief them after the investigation, revealing the purpose and allowing questions.
伦理规范与 WJEC 对负责任研究的强调相一致。如果你记录选择，使用编号代替姓名。在研究收入或消费习惯等敏感话题时，允许参与者跳过问题。调查结束后向他们进行解释，揭示研究目的并接纳提问。
5. Developing Hypotheses | 提出假设
Formulate a testable hypothesis, often stated as a null hypothesis (H₀) and an alternative hypothesis (H₁). For example: H₀ = Changing the number of sellers does not affect the average transaction price. H₁ = Increasing the number of sellers lowers the average transaction price.
提出一个可检验的假设，通常以零假设（H₀）和备择假设（H₁）的形式表述。例如：H₀ = 改变卖方数量不影响平均成交价格。H₁ = 增加卖方数量会降低平均成交价格。
The hypothesis must predict a direction or a difference. Ground it in economic theory – in this case, the supply curve shifting right leads to a lower equilibrium price. A well-built hypothesis guides the entire investigation and makes data analysis purposeful.
该假设必须预测一个方向或差异。将其建立在经济理论的基础上——在本例中，供给曲线向右移动会导致更低的均衡价格。一个构建良好的假设会指导整个调查，并使数据分析目标明确。
6. Variables and Controls | 变量与控制
Identify the independent variable (what you change, e.g., number of sellers), the dependent variable (what you measure, e.g., equilibrium price), and the control variables (what you keep constant, e.g., total number of buyers, initial money endowments, product description).
识别自变量（你改变的因素，如卖方数量）、因变量（你测量的结果，如均衡价格）以及控制变量（你保持不变的因素，如买方总数、初始资金禀赋、产品描述）。
Failing to control variables leads to confounding effects. If you also change the product quality while adding sellers, you cannot tell whether price changes come from supply or from perceived value. A clear variables table will help you stay organised and will impress the WJEC examiner.
未能控制变量会导致混杂效应。如果你在增加卖方的同时也改变了产品质量，你就无法分辨价格变化是源于供给还是感知价值。一个清晰的变量表将帮助你保持条理，并给 WJEC 考官留下深刻印象。
7. Data Collection Methods | 数据收集方法
Common instruments include observation sheets, trading records, questionnaires, and computer-based tools. For a classroom market, prepare a trading log to record each transaction’s price, buyer ID, and seller ID. For surveys, use a mix of closed questions (multiple choice, Likert scales) and one open-ended question.
常用的工具包括观察记录表、交易记录、问卷和基于计算机的工具。对于课堂市场，准备一份交易日志，记录每笔交易的价格、买方编号和卖方编号。对于问卷调查，混合使用封闭式问题（选择题、李克特量表）和一个开放式问题。
Pilot your instrument before the full investigation to catch ambiguous wording or missing options. For instance, if you ask ‘How much do you save weekly?’ and provide bands like £0–£5, £5–£10, ensure bands are mutually exclusive and exhaustive. Pilot data also helps you estimate timing and sample size.
在正式调查前对工具进行试点测试，以发现模棱两可的措辞或缺失的选项。例如，如果你问“你每周储蓄多少？”并提供类似 £0–£5、£5–£10 的区间，确保各区间互斥且穷尽。试点数据也有助于你估算时间和样本量。
8. Running the Investigation | 开展调查
On the day, set up the room to match your design. Give clear, scripted instructions so every participant receives the same information. In a double-auction market, explain the rules: buyers aim to buy below their private value, sellers aim to sell above their cost, and trades occur when a buyer and seller agree on a price.
在调查当天，按照你的设计布置教室。给出清晰、照着念的指令，确保每位参与者得到相同的信息。在双向拍卖市场中，解释规则：买方力求以低于其私人价值的价格购买，卖方力求以高于其成本的价格出售，当买卖双方就价格达成一致时交易发生。
Stay neutral during the experiment; do not influence decisions. If using periods (trading rounds), reset endowments each round and stick to the same time limit. Carefully record all transactions and any unexpected events, as these will be useful when discussing limitations in your evaluation.
在实验过程中保持中立；不要影响决策。如果采用多期（多轮交易），每轮重置初始禀赋并遵守相同的时间限制。仔细记录所有交易和任何意外事件，因为它们在评估环节讨论局限性时会很有用。
9. Organising and Presenting Data | 整理与呈现数据
Transfer raw data into a spreadsheet. Calculate the mean equilibrium price for each treatment condition. Construct a summary table showing central tendency and spread (e.g., mean, median, range). For WJEC, you are expected to present data in clear tables and graphs, like bar charts or line graphs comparing treatments.
将原始数据录入电子表格。计算每种处理条件下的平均均衡价格。构建一个显示集中趋势和离散程度（如平均值、中位数、极差）的汇总表。对于 WJEC，你应该在清晰的表格和图表中展示数据，例如对比处理条件的条形图或折线图。
Label axes fully, include units, and write a brief descriptive title. If your data shows a clear trend – say, average price falls from £6.20 to £4.50 as sellers increase from 3 to 7 – visualise this with a downward-sloping line. Avoid 3D effects and unnecessary decoration; clarity is the priority.
完整标注坐标轴、包含单位，并写出一个简明的描述性标题。如果你的数据显示出清晰的趋势——例如，当卖方从 3 个增加到 7 个时，平均价格从 £6.20 下降到 £4.50——用一条向下倾斜的线条将其可视化。避免三维效果和不必要的装饰；清晰是第一位的。
10. Analysing Results and Drawing Conclusions | 分析结果并得出结论
Compare your findings with the hypothesis. Did the data support H₁? Calculate the percentage change in the dependent variable to quantify the effect. For the seller example: a price drop from £6.20 to £4.50 is a 27.4% decrease. Mention whether the result is economically significant, not just numerically different.
将你的发现与假设进行对比。数据是否支持 H₁？计算因变量的百分比变化，以量化效果。以卖方案例为例：价格从 £6.20 下降到 £4.50，降幅为 27.4%。说明结果是否具有经济意义上的显著性，而不仅仅是数字差异。
Refer back to economic theory – the outcome matches the prediction of the supply-demand model. If results contradict the hypothesis, explore why: perhaps participants misunderstood the instructions, or demand conditions shifted unexpectedly. Acknowledging such anomalies shows critical thinking, a high-order skill prized by WJEC.
回溯经济理论——该结果符合供需模型的预测。如果结果与假设相悖，探究原因：或许参与者误读了指令，或者需求条件意外发生了变化。承认此类异常情况展现了批判性思维，这是 WJEC 重视的高阶技能。
11. Evaluating Limitations and Improvements | 评估局限性与改进
No investigation is perfect. Discuss sample size: a class of 20 may not represent the wider population, so results lack external validity. Mention demand characteristics: participants might guess the purpose and act ‘helpfully’. Acknowledge time constraints that limited the number of trading rounds.
没有哪项调查是完美的。讨论样本量：一个 20 人的班级可能无法代表更广泛的人群，因此结果缺乏外部有效性。提及需求特征：参与者可能猜出实验目的并做出“有帮助的”行为。承认时间限制影响了交易轮次的数量。
Suggest realistic improvements: repeat with multiple classes, introduce a neutral script to reduce experimenter bias, or use real money (if permitted) to strengthen incentives. Linking criticisms directly to your own procedure demonstrates reflection and earns higher evaluation marks in WJEC coursework-style tasks.
提出切合实际的改进方案：在不同班级重复实验、引入中性脚本以减少实验者偏差，或（若允许）使用真实货币来增强激励。将批评直接与你的具体操作联系起来，能体现反思精神，并在 WJEC 课程作业式任务中获得更高的评估分数。
12. Connecting to WJEC Exam Skills | 与 WJEC 考试技能的衔接
WJEC IGCSE Economics exam questions, especially the ‘analyse’ and ‘evaluate’ ones, benefit from an investigative mindset. When you have designed and run an experiment, you instinctively think about cause and effect, data reliability, and the limits of models – all directly transferable to Paper 1 and Paper 2.
WJEC IGCSE 经济学的考试题目，特别是“分析”和“评价”类题目，受益于调查性思维。当你亲自设计并开展过一次实验后，你会本能地思考因果关系、数据可靠性以及模型的局限性——所有这些能力都能直接迁移到试卷一和试卷二中。
Use the language of investigation in your essays: ‘one could test this by…’, ‘the evidence from a classroom market suggests…’, ‘however, the sample may not capture…’. This approach shows application, the second assessment objective, and helps you stand out as a reflective learner.
在论文写作中使用调查性语言：“人们可以通过……来检验这一点”，“来自课堂市场的证据表明……”“然而，样本可能并未涵盖……”。这种方法展示了应用能力（第二项评估目标），并有助于你作为一个善于反思的学习者脱颖而出。
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