📚 A-Level WJEC Psychology: Experimental / Practical Assessment Essentials | A-Level WJEC 心理学：实验/实践考核要点
In WJEC A-Level Psychology, the practical assessment component requires you to demonstrate a solid grasp of research methods by planning, conducting, and evaluating your own small-scale investigation. This article distils the essential points you must master to perform confidently, from formulating hypotheses and controlling variables to handling ethical issues and presenting data effectively. Use it as a checklist and revision guide for your personal investigation or examined practical questions.
在 WJEC A-Level 心理学课程中，实践考核部分要求你通过计划、实施和评估自己的小规模研究，来展示对研究方法的扎实掌握。本文提炼了必须掌握的关键要点，从提出假设、控制变量到处理伦理问题和有效呈现数据。你可以把它当作个人调查或考试中实践题的检查清单和复习指南。
1. Understanding the Research Process | 理解研究过程
The practical assessment in WJEC Psychology is not just about running a study; it is about understanding the entire research cycle. You need to show how psychological questions arise from theories or everyday life, and how they can be turned into testable investigations.
WJEC 心理学的实践考核不仅仅是执行一项研究，而是要理解整个研究循环。你需要展示心理学问题如何从理论或日常生活中产生，以及它们如何转变为可检验的调查。
You are expected to follow a logical sequence: identifying a research aim, reviewing relevant background literature, designing the method, collecting data, analysing results, drawing conclusions, and evaluating the process. Each stage must be justified and clearly linked to the next.
要求你遵循一个逻辑顺序：确定研究目的、回顾相关背景文献、设计方法、收集数据、分析结果、得出结论并评估整个过程。每个阶段都必须有依据，并与前后阶段清晰关联。
2. Formulating Research Questions and Hypotheses | 提出研究问题和假设
Everything begins with a well-defined research question. A vague question leads to unfocused methods, so you must phrase it precisely. The research question should indicate the variables of interest and the direction of the relationship being explored.
一切都始于一个明确的研究问题。含糊的问题会导致方法不集中，因此必须精确表述。研究问题应指明感兴趣的变量和正在探索的关系方向。
From the research question you will derive a testable hypothesis. In WJEC assessments, you need to be able to write both experimental (alternative) and null hypotheses. An experimental hypothesis predicts a difference or relationship, while the null hypothesis predicts no difference or no relationship. For example:
从研究问题中你会得出一个可检验的假设。在 WJEC 考核中，你需要能够写出实验假设（替代假设）和零假设。实验假设预测有差异或关系，而零假设预测没有差异或没有关系。例如：
Experimental: Participants who drink 200 ml of water will recall significantly more words from a list than those who drink no water.
Null: There will be no significant difference in the number of words recalled between participants who drink 200 ml of water and those who drink no water.
Always state whether your hypothesis is one-tailed (directional) or two-tailed (non-directional) and justify your choice based on previous research.
始终要说明你的假设是单尾（定向）还是双尾（非定向）的，并根据先前的研究论证你的选择。
3. Identifying and Operationalising Variables | 识别和操作化变量
Once you have a hypothesis, you must identify and operationalise the independent variable (IV) and dependent variable (DV). In an experiment, the IV is the factor you manipulate, and the DV is what you measure to see the effect of that manipulation.
一旦有了假设，就必须识别并操作化自变量（IV）和因变量（DV）。在实验中，IV是你操纵的因素，DV是你为观察该操纵效果而测量的东西。
Operationalisation means defining exactly how you will change the IV and how you will record the DV so that another researcher could replicate your study without confusion. For instance, instead of saying ‘memory performance’, operationalise it as ‘the number of words correctly recalled from a 20-word list after a 30-second delay’.
操作化意味着精确定义你将如何改变IV以及如何记录DV，以便另一位研究者可以毫无困惑地复制你的研究。例如，不要说“记忆表现”，而应操作化为“在30秒延迟后，从20词列表中正确回忆的单词数量”。
- Independent variable (IV): The condition participants are assigned to (e.g. water vs. no water). / 自变量（IV）：参与者被分配到的条件（例如，喝水 vs. 不喝水）。
- Dependent variable (DV): The number of words correctly recalled. / 因变量（DV）：正确回忆的单词数量。
You must also consider potential extraneous variables — any other factors that could influence the DV, such as time of day, noise, or participant motivation. Controlling these variables increases the internal validity of your study.
你还必须考虑潜在的额外变量——任何其他可能影响DV的因素，如一天中的时段、噪音或参与者动机。控制这些变量可以提高研究的内部效度。
4. Choosing an Experimental Design | 选择实验设计
Your choice of experimental design determines how participants are allocated to conditions. The three main designs you need to know for WJEC are independent groups, repeated measures, and matched pairs. Each has strengths and weaknesses, and your decision must be justified.
你对实验设计的选择决定了参与者如何被分配到各个条件。WJEC课程要求你了解的三种主要设计是独立组设计、重复测量设计和匹配对设计。每种设计都有优缺点，你的决定必须有理有据。
| Design / 设计 | Features / 特点 | Key Control Issue / 关键控制问题 |
|---|---|---|
| Independent Groups / 独立组 | Different participants in each condition. / 每种条件使用不同参与者。 | Participant variables (e.g. individual differences) — use random allocation. / 参与者变量（如个体差异）——使用随机分配。 |
| Repeated Measures / 重复测量 | Same participants take part in all conditions. / 同一组参与者参加所有条件。 | Order effects (practice, fatigue) — use counterbalancing. / 顺序效应（练习、疲劳）——使用平衡抵消法。 |
| Matched Pairs / 匹配对 | Participants are paired on a relevant variable, then each member goes to a different condition. / 参与者按相关变量配对，然后每对成员分配到不同条件。 | Matching is never perfect; time-consuming. / 匹配从不完美；耗时。 |
Make sure you can explain how your chosen design controls for specific extraneous variables and what limitations it introduces.
确保你能解释所选设计如何控制特定的额外变量，以及它带来了哪些局限。
5. Sampling Techniques and Participant Recruitment | 抽样技术与参与者招募
The group of people who take part in your study is the sample, drawn from a target population. The method you use to select this sample affects how well you can generalise your findings.
参与你研究的人群就是样本，来自目标人群。你用来选择样本的方法会影响你研究结论的推广程度。
- Opportunity sampling: using people who are readily available (e.g. fellow students). Quick but often biased. / 机会抽样：使用容易接触到的人（例如同学）。快速但有偏差。
- Volunteer sampling: participants self-select after seeing an advertisement. May attract a particular type of person. / 志愿者抽样：参与者在看到广告后自我选择。可能吸引某种特定类型的人。
- Random sampling: every member of the target population has an equal chance of being selected. Reduces bias but is often impractical. / 随机抽样：目标人群中的每个成员都有同等被选中的机会。减少偏差，但往往不切实际。
- Stratified sampling: identifying subgroups and selecting proportionally from each. Represents the population well but requires detailed population data. / 分层抽样：识别亚组并按比例从每个亚组中选取。能很好地代表人群，但需要详细的人口数据。
For your WJEC practical, you will most likely use opportunity sampling due to time constraints, but you must acknowledge its limitations, such as a lack of representativeness and consequent low population validity.
在你的WJEC实践研究中，由于时间限制，你最可能使用机会抽样，但必须承认其局限性，例如缺乏代表性以及因此导致的人群效度低。
6. Ethical Considerations in Practice | 实践中的伦理考量
All psychological research must adhere to ethical guidelines. WJEC expects you to identify the relevant British Psychological Society (BPS) principles and explain how you would implement them in your own investigation.
所有心理学研究都必须遵守伦理准则。WJEC要求你识别相关的英国心理学会（BPS）原则，并解释你将如何在自己的调查中实施这些原则。
Key ethical issues include informed consent, the right to withdraw, protection from harm, confidentiality, and debriefing. You need to think practically: how would you obtain consent? If the study involves mild deception, how will you justify it and debrief participants afterwards?
关键的伦理问题包括知情同意、退出权利、免受伤害、保密以及事后解说。你需要实际思考：你将如何获得同意？如果研究涉及轻微欺骗，你将如何证明其合理性并随后为参与者解说？
For example, you might prepare a standardised consent form explaining the general purpose of the study without revealing the full hypothesis, and remind participants they can leave at any time. After data collection, a debrief sheet can reveal the true aim and allow participants to ask questions or withdraw their data.
例如，你可能准备一份标准化的同意书，解释研究的一般目的而不透露完整假设，并提醒参与者他们可以随时退出。数据收集后，一份事后解说单可以揭示真实目的，并允许参与者提问或撤回他们的数据。
Always conduct a cost-benefit analysis even for a classroom practical: the psychological harm must be no greater than what participants would encounter in everyday life, and the benefits of the research should outweigh any temporary discomfort.
即使是课堂实践，也要始终进行成本效益分析：心理伤害不得大于参与者在日常生活中可能遇到的，并且研究的益处应超过任何暂时的不适。
7. Data Collection Methods and Apparatus | 数据收集方法与器材
Your chosen method must be appropriate for testing your hypothesis. In the WJEC practical context, you might use a laboratory experiment, a field experiment, a natural experiment, or a quasi-experiment. Clarify the level of control you have over the IV.
你选择的方法必须适合检验你的假设。在WJEC实践情境中，你可能使用实验室实验、现场实验、自然实验或准实验。要明确你对IV的控制程度。
Describe the apparatus and materials precisely: word lists, stopwatches, questionnaires, videos, or computer-based tasks. Standardised instructions (sometimes called a ‘brief’) are crucial to ensure that all participants are treated identically except for the manipulation of the IV. Provide a sample of these instructions in your write-up.
精确描述器材和材料：单词列表、秒表、问卷、视频或基于电脑的任务。标准化指示（有时称为“简要说明”）至关重要，以确保除了操纵IV之外，所有参与者都被同等对待。在你的报告中提供这些指示的样本。
Consider also the recording method. Will you measure reaction time in milliseconds, count correct answers, or use a rating scale? For observations, detail the behavioural categories and whether you will use time sampling or event sampling.
还要考虑记录方法。你是以毫秒为单位测量反应时间，计数正确答案，还是使用评定量表？对于观察法，要详细说明行为类别，以及你将使用时间抽样还是事件抽样。
8. Descriptive and Simple Inferential Statistics | 描述统计与简单推断统计
Once data are collected, you need to summarise them using descriptive statistics. At the very least, calculate the measure of central tendency (mean, median, or mode) that best fits your level of data, and a measure of dispersion (range or standard deviation).
一旦收集到数据，你需要使用描述统计来总结。至少要计算最适合你数据层次的集中趋势测量（平均值、中位数或众数）和离散程度测量（范围或标准差）。
For nominal data (categories), use the mode. For ordinal data (ranked) or non-normal interval data, the median is appropriate. The mean should only be used for interval data that is normally distributed without extreme outliers. Justifying your choice of descriptive statistic is a common WJEC mark point.
对于名义数据（类别），使用众数。对于顺序数据（排序的）或非正态区间数据，中位数是恰当的。平均值只应用于无极端离群值的正态分布区间数据。证明你选择描述统计的合理性是WJEC常见的给分点。
You are also likely to need a simple inferential test to determine whether your results are statistically significant. The test you choose depends on your design and data level. Common non-parametric tests for classroom practicals include:
你可能还需要一个简单的推断检验来确定结果是否具有统计显著性。检验方法的选择取决于你的设计和数据水平。课堂实践中常见的非参数检验包括：
- Chi-squared (χ²): test of association or difference with independent groups and nominal data. / 卡方检验：用于独立组和名义数据的关联性或差异检验。
- Mann-Whitney U: difference between two independent groups with ordinal data. / 曼-惠特尼U检验：用于两组独立组和顺序数据的差异。
- Wilcoxon signed-rank: difference between two conditions with repeated measures and ordinal data. / 威尔科克森符号秩检验：用于重复测量和顺序数据的两种条件差异。
- Spearman’s rho (ρ): correlation between two ordinal variables. / 斯皮尔曼等级相关系数：两个顺序变量之间的相关。
You should state the observed value, compare it to a critical value table, and decide whether to accept or reject the null hypothesis at a given significance level (typically p ≤ 0.05). Remember to report the degrees of freedom or N where appropriate.
你应该说明观察值，将其与临界值表进行比较，并在给定的显著性水平（通常 p ≤ 0.05）下决定接受或拒绝零假设。记住在适当的地方报告自由度或样本量N。
9. Presenting Findings: Tables and Graphs | 呈现发现：表格与图形
Data must be presented so that trends and patterns are immediately clear. WJEC expects you to produce accurate and fully labelled summary tables, bar charts, histograms, or scatterplots depending on the type of data.
数据的呈现应使趋势和模式一目了然。WJEC要求你根据数据类型，制作准确且完整标注的汇总表、条形图、直方图或散点图。
A good summary table includes descriptive statistics for each condition; for instance, the mean number of words recalled and the standard deviation. All tables should have a clear title and labelled rows and columns with units where appropriate.
一个好的汇总表包括每种条件的描述统计量；例如，回忆单词的平均数量与标准差。所有表格都应有清晰的标题，行列标注清晰，并在适当处标明单位。
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