📚 Year 9 OCR Statistics: Glossary Quick-Memorisation Guide | 词汇术语速记指南
Mastering statistical vocabulary is the first step to excelling in your OCR Year 9 statistics course. This guide pairs key terms with clear, memorable explanations in both English and Chinese, helping you recall definitions quickly and apply them confidently in exam questions. Each section introduces a cluster of related terms, builds your understanding step by step, and reinforces the language you will meet on papers.
掌握统计学术语是你在OCR九年级统计课程中脱颖而出的第一步。这份指南为关键术语配上了清晰易记的中英双语解释，帮助你快速回忆定义并在考试题目中自信运用。每一节介绍一组相关词汇，逐步建立你的理解，并巩固你在试卷中会遇到的语言。
1. Mean, Median, Mode | 平均数、中位数、众数
The mean values divided by the number of values. It is often called the average and is written as x̄ = (∑x) / n, where ∑x means 'sum of x' and n is the count.
平均数是所有数据值之和除以数值的个数。它常被称为平均值，写作 x̄ = (∑x) / n，其中 ∑x 表示 x 的总和，n 是数据个数。
The median is the middle value when the data are arranged in order. If there are two middle numbers, you take their mean. The median is less affected by extreme values than the mean.
中位数是将数据按顺序排列后中间的值。如果有两个中间数，就取它们的平均数。与平均数相比，中位数受极端值的影响更小。
The mode is the value that occurs most often. A set of data can have no mode, one mode (unimodal), or more than one mode (bimodal or multimodal). Mode is the only measure of average that works for non‑numerical data.
众数是出现次数最多的值。一组数据可以没有众数，有一个众数（单峰），或多个众数（双峰或多峰）。众数是唯一适用于非数值数据的平均数。
2. Range and Interquartile Range | 极差与四分位距
The range is the difference between the largest and smallest values. It gives a quick sense of spread but can be distorted by outliers.
极差是最大值与最小值之间的差值。它能快速反映数据的分散程度，但可能被异常值扭曲。
The interquartile range (IQR) is the range of the middle 50% ₃ − Q₁, where Q₁ is the lower quartile (25th percentile) and Q₃ is the upper quartile (75th percentile). The IQR is a more robust measure of spread.
四分位距（IQR）是数据中间50%的范围。计算公式为 IQR = Q₃ − Q₁，其中 Q₁ 为下四分位数（第25百分位数），Q₃ 为上四分位数（第75百分位数）。IQR 是一种更稳健的离散度量。
To find Q₁, you find the median of the lower half of the data; for Q₃, you find the median of the upper half. If the number of data points leaves a middle value, it is not included in either half when calculating quartiles in OCR.
寻找 Q₁ 时，取数据下半部分的中位数；寻找 Q₃ 时，取上半部分的中位数。按照OCR的规定，如果数据点数量让中间值单独存在，计算四分位数时，这个中间值不计入上下半部分。
3. Box Plots (Box‑and‑Whisker Diagrams) | 箱线图
A box plot displays the five‑number summary: minimum, lower quartile (Q₁), median (Q₂), upper quartile (Q₃), and maximum. The box is drawn from Q₁ to Q₃ with a line at the median. The whiskers extend to the minimum and maximum, unless outliers are marked separately.
箱线图展示了五数概括：最小值、下四分位数（Q₁）、中位数（Q₂）、上四分位数（Q₃）和最大值。箱子从 Q₁ 画到 Q₃，中间用一条线标出中位数。须线延伸到最小值和最大值，除非异常值被单独标出。
Box plots make it easy to compare distributions, see skewness, and identify outliers. An outlier is a value that lies more than 1.5 × IQR below Q₁ or above Q₃.
箱线图便于比较分布、观察偏态和识别异常值。异常值是指低于 Q₁ − 1.5×IQR 或高于 Q₃ + 1.5×IQR 的数值。
When comparing box plots, comment on medians (central tendency), IQRs (spread), and any differences in whisker length or outliers.
在比较箱线图时，需评论中位数（集中趋势）、IQR（离散程度），以及须线长度或异常值的差异。
4. Probability Basics | 概率基础
Probability measures how likely an event is, always between 0 (impossible) and 1 (certain). It may be written as a fraction, decimal, or percentage.
概率衡量一个事件发生的可能性，取值总是在0（不可能）到1（必然）之间。它可以写成分数、小数或百分数。
An experiment is a repeatable process with observable results. A single trial is one performance of the experiment. An outcome is a possible result, and an event is a set of one or more outcomes.
试验是一个可重复的过程，会产生可观察的结果。一次试次是试验的一次执行。结果是一个可能的结果，而事件是一个或多个结果的集合。
vourable outcomes / total number of possible outcomes, provided all outcomes are equally likely.
事件的概率 = 有利结果的数量 / 所有可能结果的总数，前提是所有结果是等可能的。
5. Sample Space and Events | 样本空间与事件
The sample space (often denoted S or Ω) is the set of all possible outcomes of an experiment. For rolling a fair six‑sided die, the sample space is {1, 2, 3, 4, 5, 6}.
样本空间（常用 S 或 Ω 表示）是试验所有可能结果的集合。掷一枚公平六面骰子，样本空间为 {1, 2, 3, 4, 5, 6}。
An event is a subset of the sample space. For example, 'rolling an even number' corresponds to the event {2, 4, 6}. The complement of event A, written A', is all outcomes not in A.
事件是样本空间的一个子集。例如，“掷出偶数”对应事件 {2, 4, 6}。事件 A 的补集，写作 A'，是不在 A 中的所有结果。
Two events are mutually exclusive if they cannot happen at the same time. P(A ∩ B) = 0 for mutually exclusive A and B.
如果两个事件不能同时发生，则它们是互斥的。对于互斥事件 A 和 B，有 P(A ∩ B) = 0。
6. Tree Diagrams | 树形图
A tree diagram shows all possible outcomes of a sequence of events using branches. The probabilities are written on the branches and must sum to 1 at each branch point.
树形图使用分支来展示一连串事件所有可能的结果。概率标在分支上，且在每个分支点上的概率之和必须为1。
To find the probability of a combination of outcomes, multiply the probabilities along the branches. To find the probability of an event that can occur in several ways, add the probabilities of the relevant branches.
要找出结果组合的概率，将沿途分支上的概率相乘。若某个事件可能通过多种途径发生，则将这些相关分支的概率相加。
Tree diagrams are especially useful for independent events and for solving conditional probability problems at a basic level.
树形图在分析独立事件和处理基础层面的条件概率问题时尤其有用。
7. Mutually Exclusive Events and the Addition Rule | 互斥事件与加法法则
wo events A and B are mutually exclusive, the probability that either A or B occurs is P(A ∪ B) = P(A) + P(B). The '∪' symbol means 'union' (A or B or both).
如果两个事件 A 与 B 互斥，那么 A 或 B 发生的概率为 P(A ∪ B) = P(A) + P(B)。符号 '∪' 表示“并集”（A 或 B 或两者）。
If events are not mutually exclusive, you must subtract the overlap: P(A ∪ B) = P(A) + P(B) − P(A ∩ B), where '∩' is the intersection (A and B).
如果事件不是互斥的，则必须减去重叠部分：P(A ∪ B) = P(A) + P(B) − P(A ∩ B)，其中 '∩' 表示交集（A 与 B 同时发生）。
A quick memory tip: 'OR' means add (and subtract the intersection if they overlap) – think of the word 'union' as adding together.
快速记忆法：“或”意味着相加（如果重叠则减去交集）——将“并集”一词理解为加合。
8. Independent Events and the Multiplication Rule | 独立事件与乘法法则
Two events are independent ccurrence of one does not affect the probability of the other. For independent events, P(A ∩ B) = P(A) × P(B).
如果一个事件的发生不影响另一个事件发生的概率，则这两个事件是独立的。对于独立事件，P(A ∩ B) = P(A) × P(B)。
s to identify independence from a question description or from given probabilities. If P(A ∩ B) equals P(A) × P(B), the events are independent.
考试中常见的任务是，从题目描述或给定概率中识别独立性。如果 P(A ∩ B) 等于 P(A) × P(B)，则事件独立。
Memory phrase: 'AND' means multiply, but only if the events are independent – check that the outcome of one does not change the probability of the other.
记忆口诀：“且”意味着相乘，但仅当事件独立时成立——确认一个事件的结果不会改变另一个事件的概率。
9. Data Collection Terms | 数据收集术语
A population is the whole set of individuals or items that you want to study. A sample is a subset of the population, chosen to represent it. A census collects data from every member of the population.
总体是你想研究的全部个体或项目的集合。样本是从总体中选出的、用于代表总体的子集。普查则从总体的每一个成员收集数据。
A good sample should be random and large enough to reflect the population accurately. Bias occurs when a sampling method systematically over‑ or under‑represents certain groups.
一个好的样本应是随机的，并且足够大以准确反映总体。当抽样方法系统性地过多或过少代表某些群体时，就会产生偏差。
Common sampling methods in OCR include simple random sampling, stratified sampling (where population is divided into groups and samples taken from each), and systematic sampling.
OCR中常见的抽样方法包括简单随机抽样、分层抽样（将总体分组，然后从每组抽样）和系统抽样。
10. Charts and Graphs Vocabulary | 图表词汇
A bar chart uses bars of equal width to show frequencies for distinct categories. The height of each bar represents frequency. Bars do not touch, unlike a histogram.
条形图用等宽的条状表示不同类别的频数。每个条的高度代表频数。与直方图不同，条形图的条形之间不接触。
A pie chart e each slice’s angle is proportional to the frequency. Angle = (frequency / total) × 360°.
饼图将数据显示为一个圆形的扇区，每个扇区的角度与频数成比例。角度 = (频数 / 总数) × 360°。
A line graph shows how a variable changes over time. Points are plotted and joined by lines. A scatter graph (scatter plot) is used to explore the relationship between two numerical variables.
折线图显示一个变量随时间变化的趋势。先描点，再用线段连接。散点图用于探索两个数值变量之间的关系。
Correlation describes the strength and direction of a linear relationship: positive, negative, or none. Correlation does not imply causation – a key exam phrase!
相关性描述线性关系的强度和方向：正相关、负相关或无相关。相关性并不意味着因果关系——这是考试中的关键表述！
11. Key Statistical Notation | 关键统计符号
speeds up exam work. ∑x denotes the sum of all x values; n is the number of data points; x̄ is the sample mean. For data in a frequency table: ∑fx means 'frequency × value' summed.
熟悉符号能提高解题速度。∑x 表示所有 x 值的总和；n 为数据点的个数；x̄ 为样本平均数。对于频数表中的数据：∑fx 表示“频数 × 值”的总和。
The variance and standard deviation are often introduced later, but Year 9 may touch on range and IQR as the main measures of spread. The symbol σ is the population standard deviation, s is the sample standard deviation.
方差和标准差通常稍后引入，但九年级可能主要使用极差和IQR作为离散度量。符号 σ 为总体标准差，s 为样本标准差。
Probabilistic notation: P(A) means probability of event A; P(A') means complement; P(A|B) is 'probability of A given B' – used for conditional probability.
概率符号：P(A) 表示事件 A 的概率；P(A') 表示补集；P(A|B) 表示“给定 B 时 A 的概率”——用于条件概率。
12. Memorisation Quick‑Tips | 速记技巧
Use mnemonic sentences: 'Mighty Elephants Munch' → Mean, Median, Mode. 'Queen Rules Quietly' new vocabulary to vivid images; for instance, picture a box with whiskers for a box plot.
使用记忆句：“Mighty Elephants Munch”（强大的大象咀嚼）→ 平均数、中位数、众数。“Queen Rules Quietly”（女王安静统治）→ 四分位数、极差、四分位距。将新词汇与生动的画面联系起来；比如，为箱线图想象一个长胡须的盒子。
Create flashcards with the English term on one side, the Chinese equivalent and a simple definition on the reverse. Practise saying the words aloud as you read them – combining visual and auditory learning strengthens recall.
制作闪卡，正面写英文术语，背面写对应的中文和简单定义。阅读时大声念出词汇——将视觉与听觉学习结合，能强化记忆。
Finally, always write out the formulae with Unicode symbols (e.g., x̄ Q₁) rather than just reading them. Repeated writing builds automaticity for the exam hall.
最后，总是用 Unicode 符号写出公式（如 x̄、∑、σ、Q₁），而不仅仅是用眼睛看。反复书写能为考场培养自动化反应。
Published by TutorHao | Statistics Revision Series | aleveler.com
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