📚 A-Level AQA Economics: Experimental Method Guide | A-Level AQA 经济：实验操作指南
In AQA A-Level Economics, the experimental method is not about mixing chemicals, but about investigating economic behaviour through controlled setups where researchers manipulate one variable to observe its effect on another. This guide will walk you through the types of experiments, how to design them, analyse data, and apply your understanding to exam questions on behavioural, labour, and development economics.
在 AQA A-Level 经济学中，实验方法并不是在混合化学试剂，而是通过控制情境，研究者操纵一个变量来观察其对另一个变量的影响，从而探究经济行为。本指南将带你了解实验的类型、如何设计实验、分析数据，并将你的理解应用到行为经济学、劳动经济学和发展经济学相关的考试题目中。
1. Why Experiments Matter in Economics | 为什么实验在经济学中重要
Traditional economics relies on observational data from real markets, which often suffers from endogeneity and omitted variable bias. Experiments, by randomly assigning subjects to treatment and control groups, allow economists to establish causality. For your AQA exam, you need to appreciate how experiments help test theories like rationality, fairness, or the impact of incentives on productivity.
传统经济学依赖来自真实市场的观察数据，这些数据常常存在内生性和遗漏变量偏差。实验通过将受试者随机分配到处理组和对照组，使经济学家能够建立因果关系。对于你的 AQA 考试，你需要理解实验如何帮助检验诸如理性、公平，或激励对生产率影响等理论。
2. Types of Experiments in AQA Economics | AQA 经济学中的实验类型
The AQA specification distinguishes between laboratory experiments, field experiments, and natural experiments (or quasi-experiments). You must be able to compare their internal and external validity. A lab experiment offers high control but may lack realism; a field experiment takes place in a natural setting, improving realism but often reducing control. Natural experiments exploit external shocks (like a policy change) that create ‘as-if random’ treatment.
AQA 大纲区分了实验室实验、实地实验和自然实验（或准实验）。你必须能够比较它们的内部效度和外部效度。实验室实验提供了高度控制，但可能缺乏现实性；实地实验在自然环境中进行，提高了现实性，但常常降低了控制。自然实验利用外生冲击（如政策变化）创造出 “仿佛随机” 的处理组。
3. Key Features of a Lab Experiment | 实验室实验的关键特征
Participants are recruited into an artificial environment where the researcher controls the independent variable and randomly allocates individuals to treatment and control groups. For example, testing the impact of different tax rates on work effort using a computer task. The strength is high internal validity – you can be confident that the treatment caused the observed effect.
受试者被招募到一个人工环境中，研究者控制自变量并随机将个体分配到处理组和对照组。例如，使用计算机任务测试不同税率对工作努力程度的影响。其优势在于高内部效度 —— 你可以确信处理组导致了观察到的效应。
4. Field Experiments and Their Real-World Power | 实地实验及其现实力量
Field experiments take the manipulation into a real-life economic setting. A famous example is testing the impact of performance pay on worker output in a factory. Participants often do not know they are in an experiment, reducing demand effects. However, ethical concerns arise and controlling extraneous variables is harder. AQA expects you to discuss trade-offs between control and authenticity.
实地实验将操纵带入真实的经济环境。一个著名例子是测试绩效工资对工厂工人产出的影响。受试者通常不知道自己在参与实验，减少了需求效应。然而，伦理问题会出现，控制外来变量也更困难。AQA 期望你讨论控制与真实性之间的权衡。
5. Natural and Quasi-Experiments | 自然实验与准实验
When random assignment is unethical or impossible, economists use natural experiments. A policy change (e.g., a new minimum wage in one region but not another) creates a treatment and control group via an exogenous event. The difference-in-differences method is often applied. In exams, you might be asked to evaluate whether such a setup really mimics randomisation.
当随机分配不道德或不可能时，经济学家使用自然实验。一项政策变化（例如，仅在一个地区实施新的最低工资）通过外生事件创建了处理组和对照组。常使用双重差分法进行分析。在考试中，你可能会被要求评估这样的设计是否真的模拟了随机化。
6. Designing an Economic Experiment Step by Step | 逐步设计经济实验
First, formulate a testable hypothesis: ‘Increasing the piece rate will raise output per worker.’ Second, define the independent variable (piece rate) and dependent variable (output). Third, develop a protocol to minimise confounding variables – random assignment, identical instructions, and a controlled environment. Fourth, determine sample size to achieve statistical power.
首先，提出一个可检验的假设：“提高计件工资率将提高每个工人的产出。” 其次，定义自变量（计件工资率）和因变量（产出）。第三，制定方案以最小化混杂变量 —— 随机分配、相同的指令和受控环境。第四，确定样本量以实现统计功效。
7. Controlling Bias and Confounding Variables | 控制偏差与混杂变量
Selection bias is countered by randomisation. Demand effects occur when participants guess the aim and change behaviour; you can mitigate this by using a between-subjects design or deception (if ethically justified). The Hawthorne effect – where subjects improve performance simply because they are observed – can be addressed by having the control group also be monitored.
选择偏差通过随机化来抵消。需求效应发生在受试者猜到目的并改变行为时；可以通过使用被试间设计或在伦理允许下使用欺骗来减轻。霍桑效应 —— 即受试者仅仅因为被观察而提高绩效 —— 可以通过让对照组同样受到监测来解决。
8. Ethical Considerations in Economic Experiments | 经济实验中的伦理考量
Informed consent is vital: participants must know they can withdraw at any time. Deception should be minimised and debriefing provided. In field experiments, interventions affecting livelihoods (e.g., varying wages) must be handled sensitively. AQA questions may ask you to weigh ethical constraints against the value of causal evidence.
知情同意至关重要：受试者必须知道他们可以随时退出。应尽量减少欺骗，并提供事后说明。在实地实验中，影响生计的干预（如改变工资）必须谨慎处理。AQA 问题可能会要求你权衡伦理约束与因果证据的价值。
9. Data Analysis: From Averages to Significance | 数据分析：从均值到显著性
Compare the mean outcome of the treatment group with that of the control group. Use a t-test (or Mann-Whitney U if data are not normally distributed) to determine if the difference is statistically significant at the 5% level. Report p-values. In AQA exam essays, you should interpret ‘statistically significant’ as evidence that the null hypothesis is unlikely to be true.
比较处理组和对照组的结果均值。使用 t 检验（如果数据不呈正态分布则使用 Mann-Whitney U 检验）来判断差异在 5% 水平上是否具有统计显著性。报告 p 值。在 AQA 考试论文中，你应将 “统计显著” 解释为该零假设不太可能成立的证据。
10. Limitations of Experimental Methods | 实验方法的局限性
Low external validity is a common criticism – lab findings may not generalise to real markets. Small stakes and artificial tasks can reduce the relevance of results. Furthermore, many economic questions (e.g., the effect of interest rate changes on aggregate investment) cannot be addressed with a true experiment. You must show this nuanced evaluation to reach top marks.
低外部效度是一个常见的批评 —— 实验室的发现可能无法推广到真实市场。小额赌注和人工任务会降低结果的相关性。此外，许多经济问题（例如，利率变化对总投资的影响）无法通过真正的实验来解决。你必须展示这种细致的评估才能获得高分。
11. Linking Experiments to Behavioural Economics | 将实验与行为经济学联系起来
Experiments are the backbone of behavioural economics. Kahneman and Tversky’s prospect theory originated from experiments showing loss aversion. Dictator and ultimatum games reveal other-regarding preferences that contradict pure self-interest. In your answers, connect experimental findings to concepts like anchoring, framing, and bounded rationality.
实验是行为经济学的支柱。卡尼曼和特沃斯基的前景理论源于证明损失厌恶的实验。独裁者博弈和最后通牒博弈揭示了与纯粹自利相矛盾的他人关怀偏好。在你的答案中，将实验发现与锚定、框架效应和有限理性等概念联系起来。
12. Exam Technique for Experimental Questions | 实验类题目的考试技巧
AQA often presents a short case study describing an experiment. You will be asked to identify the hypothesis, comment on the methodology, and discuss whether the conclusions are valid and applicable. Structure your response: define the type of experiment, evaluate internal validity (randomisation, control), external validity (generalisation), and suggest improvements.
AQA 常常给出一个描述实验的简短案例研究。你将被问到识别假设、评论方法论，并讨论结论是否有效和适用。构建你的回答：定义实验类型，评估内部效度（随机化、控制），外部效度（推广性），并提出改进建议。
Published by TutorHao | Economics Revision Series | aleveler.com
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