IGCSE CAIE Psychology: Formula & Theorem Quick Reference Handbook | IGCSE CAIE 心理学：公式定理速查手册

📚 IGCSE CAIE Psychology: Formula & Theorem Quick Reference Handbook | IGCSE CAIE 心理学：公式定理速查手册

This quick reference handbook summarises the essential descriptive statistics formulas and key theoretical models that appear in the CAIE IGCSE Psychology syllabus. It is designed for rapid revision before Paper 1 and Paper 2, linking numerical skills to core psychological explanations, studies and evaluations.

本速查手册汇总了 CAIE IGCSE 心理学课程中的核心描述统计公式与关键理论模型，适合 Paper 1 与 Paper 2 考前快速复习，帮助考生将数字技能与心理学核心解释、经典研究和评价联系起来。

1. Descriptive Statistics: Mean, Median, Mode and Range | 描述统计：平均数、中位数、众数与全距

The mean is calculated by adding all scores and dividing by the number of scores. It uses every value in the data set but can be distorted by extreme outliers.

平均数是将所有分数相加后除以分数的个数。它使用数据中的每一个数值，但容易被极端异常值拉偏。

Mean = ΣX ÷ n

Here ΣX means the sum of all raw scores, and n is the number of participants or observations. The median is the middle value when data are arranged in ascending order. If there are two middle numbers, add them and divide by two.

其中 ΣX 表示所有原始分数的总和，n 表示参与者或观察次数。中位数是将数据按升序排列后位于中间的值。如果有两个中间数，则将两者相加再除以 2。

The mode is the most frequent value in a data set. A data set can have one mode, more than one mode, or no mode at all. The range is the difference between the highest and lowest scores.

众数是数据集中出现频率最高的数值。一个数据集可以有一个众数、多个众数，或者没有众数。全距是最高分与最低分之间的差值。

Range = highest score – lowest score

For example, in the data set 3, 5, 7, 9, 11, the mean is 7, the median is 7, there is no mode, and the range is 8. This shows that the mean and median can agree when the distribution is symmetrical.

例如，在数据集 3、5、7、9、11 中，平均数为 7，中位数为 7，没有众数，全距为 8。这说明当分布对称时，平均数和中位数可能相同。

2. Percentages, Ratios and Proportions | 百分比、比率与占比

IGCSE Psychology questions often ask you to calculate the percentage of participants who give a certain response. Divide the frequency of the response by the total number of participants, then multiply by 100.

IGCSE 心理学题目经常要求计算给出某种回答的参与者所占百分比。将某一回答出现的频率除以参与者总数，再乘以 100。

Percentage = (frequency ÷ total) × 100

A ratio compares two quantities. For example, if 12 participants conformed and 8 did not, the conforming-to-nonconforming ratio is 12:8, which can be simplified to 3:2. Proportions express a part of a whole as a decimal between 0 and 1. Divide the part by the whole.

比率用来比较两个数量。例如，如果 12 名参与者从众、8 名未从众，那么从众与未从众的比率为 12:8，可简化为 3:2。占比用 0 到 1 之间的小数表示整体的一部分，用部分除以整体即可。

Proportion = part ÷ whole

These three methods are common in research methods questions: they allow you to compare conditions, summarise questionnaire data and report findings clearly.

这三种方法在研究方法类题目中很常见，可以用来比较不同条件、总结问卷数据并清晰地报告研究结果。

3. Measures of Spread: Standard Deviation Basics | 离散程度：标准差基础

Standard deviation measures how much scores spread out around the mean. A small standard deviation means most scores are close to the mean; a large standard deviation means scores are widely scattered.

标准差测量分数围绕平均数的分散程度。标准差小说明大多数分数接近平均数；标准差大说明分数分布很分散。

In IGCSE Psychology you are not usually required to compute standard deviation from raw data by hand for a full data set, but you must interpret what it shows and compare distributions using it.

在 IGCSE 心理学中，通常不要求考生用原始数据手动计算完整数据集的标准差，但必须能解释标准差的含义并用它比较分布。

SD = √( Σ(x – mean)² ÷ n )

Here x is each individual score, mean is the arithmetic mean, and n is the number of scores. The symbol Σ means sum, and √ means square root. If one condition has a lower standard deviation than another, its results are more consistent.

其中 x 表示每个单独的分数，mean 表示算术平均数，n 表示分数个数。符号 Σ 表示求和，√ 表示平方根。如果一种条件的标准差低于另一种条件，说明该条件的结果更一致。

4. Multi-Store Model of Memory | 记忆的多存储模型

The Multi-Store Model of Memory (Atkinson and Shiffrin, 1968) states that memory consists of three separate stores: sensory memory, short-term memory (STM) and long-term memory (LTM). Information moves between stores through attention and rehearsal.

记忆的多存储模型（Atkinson 和 Shiffrin，1968）认为记忆由三个独立的存储系统组成：感觉记忆、短时记忆（STM）和长时记忆（LTM）。信息通过注意和复述在各个存储系统之间移动。