📚 AS Eduqas Psychology: Mastering Experimental & Practical Assessments | AS Eduqas 心理学实验与实践考核要点
Mastering experimental and practical assessment skills is essential for AS Eduqas Psychology, particularly in Component 2 where research methods and personal investigations are assessed. This guide covers key concepts from designing experiments to analysing data and evaluating methodology, ensuring you feel confident in applying psychological methods accurately.
掌握实验与实践评估技能对于 AS Eduqas 心理学至关重要，尤其是在评估研究方法和个人调查的 Component 2 中。本指南涵盖从设计实验到分析数据以及评估方法的关键概念，确保你在准确应用心理学方法时充满信心。
1. Understanding Variables | 理解变量
In any experiment, you must identify the independent variable (IV) – the factor you manipulate, and the dependent variable (DV) – the factor you measure. The IV should have at least two conditions (e.g. experimental and control).
在任何实验中，你必须识别自变量 (IV)——你操纵的因素，以及因变量 (DV)——你测量的因素。自变量应至少有两个水平（例如实验组和对照组）。
Operationalising variables means defining exactly how the IV and DV will be manipulated or measured. This allows the experiment to be replicated. For example, instead of saying “memory”, operationalise it as “number of words correctly recalled from a list of 20”.
操作化变量是指明确定义将如何操纵或测量自变量和因变量。这使实验可被重复。例如，与其说”记忆力”，不如将其操作化为”从20个单词列表中正确回忆出的单词数量”。
Extraneous variables are any factors other than the IV that could affect the DV. If they are not controlled, they become confounding variables, undermining the internal validity of the study.
额外变量是指除自变量外任何可能影响因变量的因素。如果不加以控制，它们就会成为混淆变量，破坏研究的内部效度。
2. Research Hypotheses | 研究假设
A hypothesis is a precise, testable statement predicting the relationship between variables. For an experiment, it must include both the IV and DV and be operationalised.
假设是一个精确、可检验的陈述，预测变量之间的关系。对于实验而言，它必须包含自变量和因变量，并且是可操作化的。
There are three main types: directional (one-tailed), non-directional (two-tailed), and null. A directional hypothesis states the expected direction of the effect (e.g. “caffeine increases reaction speed”), while a non-directional simply states there will be a difference (e.g. “caffeine affects reaction speed”). The null hypothesis states there will be no effect or difference, and any observed difference is due to chance.
有三种主要类型：定向（单尾）、非定向（双尾）和虚无假设。定向假设陈述预期的效应方向（例如”咖啡因提高反应速度”），而非定向假设只说明存在差异（例如”咖啡因影响反应速度”）。虚无假设陈述没有效应或差异，任何观察到的差异都是偶然造成的。
When to use each? Use a directional hypothesis when previous research clearly suggests a particular outcome. Use a non-directional when findings are mixed or the area is unexplored.
何时使用它们？当前人研究明确表明某种特定结果时，使用定向假设。当研究结果不一致或该领域尚未被探索时，使用非定向假设。
3. Experimental Designs | 实验设计
Choosing the right experimental design is crucial for controlling participant variables. The three main designs are independent groups, repeated measures, and matched pairs.
选择合适的实验设计对于控制被试变量至关重要。三种主要设计是独立组设计、重复测量设计和匹配对设计。
| Design | Key Feature | Advantage | Disadvantage |
|---|---|---|---|
| Independent Groups | Different participants in each condition | No order effects | Participant variability may confound results |
| Repeated Measures | Same participants do all conditions | Controls participant variables; fewer participants needed | Order effects (practice, fatigue) can occur |
| Matched Pairs | Twins or matched participants split into conditions | Reduces participant variability; no order effects | Time-consuming and difficult to match perfectly |
For repeated measures, counterbalancing is used to control order effects: half the participants do condition A then B, the other half do B then A. This spreads the practice and fatigue effects evenly.
对于重复测量设计，使用平衡法来控制顺序效应：一半被试先做条件A再做条件B，另一半先做B再做A。这样平均分配了练习效应和疲劳效应。
In independent groups, random allocation to conditions is essential to avoid bias. In matched pairs, you must ensure that the matching variable (e.g. IQ, age) is relevant to the DV.
在独立组设计中，随机分配被试到各个条件是避免偏差的关键。在匹配对设计中，必须确保匹配变量（如智商、年龄）与因变量相关。
4. Control of Extraneous Variables | 控制额外变量
Standardisation of procedures, instructions, and environment minimises investigator effects and situation noise. Using a standardised script ensures all participants receive the same information.
程序、指导语和环境的标准化可以最小化主试效应和情境噪音。使用标准化的指导脚本确保所有被试接收到相同的信息。
- Randomisation: Using chance methods (e.g. random number generator) to decide order of stimuli or allocation to groups.
- 随机化：使用随机方法（如随机数字生成器）决定刺激呈现顺序或分组。
- Single-blind technique: Participants do not know which condition they are in, reducing demand characteristics.
- 单盲技术：被试不知道他们处于哪个条件，从而减少需求特征。
- Double-blind technique: Neither participants nor the researcher collecting data knows the condition, controlling for both demand characteristics and investigator bias.
- 双盲技术：被试和数据收集的研究者都不知道条件，同时控制需求特征和研究者偏差。
Pilot studies are small-scale trial runs that allow you to identify potential problems with extraneous variables, instructions, or measures before the main experiment.
试点研究是小规模的试验运行，让你在主实验前识别出额外变量、指导语或测量工具的潜在问题。
5. Sampling Methods | 抽样方法
The way you select participants affects the generalisability of your findings. There are several sampling techniques, each with strengths and weaknesses.
你选择被试的方式会影响研究结果的推广性。有几种抽样技术，各有优缺点。
- Random sampling: Every member of the target population has an equal chance of selection. It’s the best for representativeness but rarely practical.
- 随机抽样：目标人群的每个成员都有同等被选中的机会。代表性最好，但很少可行。
- Opportunity sampling: Using whoever is available at the time (e.g. students in the corridor). Quick and convenient, but likely biased.
- 机会抽样：使用当时可用的人（如走廊里的学生）。快速方便，但可能产生偏差。
- Volunteer (self-selecting) sampling: Participants respond to adverts. Can attract a certain profile (motivated, curious) and may not be representative.
- 志愿者（自选）抽样：被试回应广告。可能吸引特定人群（有积极性、好奇），可能不具代表性。
- Stratified sampling: The population is divided into strata (e.g. age bands), and participants are randomly selected from each in proportion to the population. Very representative but complex.
- 分层抽样：将人群划分为不同层次（如年龄段），并按照人口比例从每层随机选择被试。非常具有代表性但复杂。
- Snowball sampling: Existing participants recruit further participants. Useful for hard-to-reach populations but lacks randomness.
- 滚雪球抽样：现有被试招募更多被试。适用于难以接触的人群，但缺乏随机性。
For your practical investigation, you are most likely to use opportunity or volunteer sampling. Always note the implications for generalisability in your evaluation.
对于你的个人调查，你很可能会使用机会抽样或志愿者抽样。在评估中务必指出这对推广性的影响。
6. Ethical Considerations | 伦理考量
All psychological research must follow BPS ethical guidelines. For your own practical, you must demonstrate awareness of these principles.
所有心理学研究都必须遵循 BPS 伦理准则。对于你自己的实践，你必须表现出对这些原则的认识。
Key issues: informed consent, deception, protection from harm, privacy and confidentiality, and the right to withdraw. Participants must give their agreement based on full knowledge of the study, though sometimes a minor deception is permitted if properly justified and followed by a thorough debrief.
关键问题：知情同意、欺骗、避免伤害、隐私与保密，以及
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