📚 Year 7 CAIE Statistics: Quick Vocabulary & Terminology Memorisation Guide | Year 7 CAIE 统计：词汇术语速记指南
Welcome to your Year 7 Statistics vocabulary guide. Mastering the key terms is the very first step towards understanding data, interpreting charts, and solving exam problems with confidence. This guide explains every essential word and phrase you are likely to meet in the CAIE course, with clear definitions and examples to help you remember them quickly.
欢迎使用七年级统计学术语指南。掌握关键术语是理解数据、解读图表并自信地解决考试问题的第一步。本指南解释了你将在 CAIE 课程中遇到的每一个重要词语和短语，配以清晰的定义和示例，帮助你快速记忆。
1. What is Statistics? | 什么是统计？
Statistics is the branch of mathematics that deals with collecting, organising, interpreting, and presenting data. In your CAIE course, you will learn to work with numbers and categories to find patterns and answer questions. The word ‘data’ means pieces of information. The singular form is ‘datum’, but we nearly always say ‘data’ for a set of values.
统计学是数学的一个分支，研究数据的收集、整理、解释和呈现。在 CAIE 课程中，你将学习处理数字和类别，以发现模式并回答问题。“数据”一词指的是信息片段。单数形式是“datum”，但我们通常用“data”来表示一组数值。
A statistic is a fact or a number that summarises some data, such as an average or a percentage. Statistics helps us make sense of the world around us, from sports scores to weather forecasts.
统计量是概括某些数据的事实或数字，例如平均数或百分比。统计学帮助我们理解周围的世界，从体育比分到天气预报。
2. Types of Data: Qualitative and Quantitative | 数据类型：定性数据与定量数据
Data can be split into two main types: qualitative and quantitative. Qualitative data (also called categorical data) describes qualities or categories. Examples include eye colour, favourite subject, and type of transport. Quantitative data is numerical and represents quantities that can be counted or measured. Examples are height in centimetres, number of siblings, and test scores.
数据可以分为两种主要类型：定性数据和定量数据。定性数据（也称为分类数据）描述性质或类别。例如眼睛颜色、最喜欢的科目和交通方式。定量数据是数值型数据，代表可计数或可测量的量。例如身高（厘米）、兄弟姐妹数量和考试分数。
When you collect data, always decide whether it is qualitative or quantitative. This choice affects which graph or average you will use later.
当你收集数据时，一定要判断它是定性的还是定量的。这个选择会影响你之后使用哪种图表或平均数。
3. Discrete vs Continuous Data | 离散数据与连续数据
Quantitative data can be further divided into discrete and continuous data. Discrete data can only take certain values, usually whole numbers. You count discrete data. For example, the number of students in a class, goals scored in a match, or shoe size (even if it has halves, the values are fixed steps). Continuous data can take any value within a range and is measured rather than counted. Examples include time taken to run 100 m, weight, temperature, and length. Continuous data can include decimals and fractions.
定量数据可进一步分为离散数据和连续数据。离散数据只能取某些值，通常是整数。离散数据是数出来的。例如，班级学生人数、比赛进球数、鞋码（即使有半码，也是固定步长的值）。连续数据可以取一个范围内的任何数值，是测量出来的而不是数出来的。例如跑 100 米的时间、体重、温度、长度。连续数据可以包含小数和分数。
A simple memory trick: if you count it, it is probably discrete. If you measure it, it is continuous.
一个简单的记忆技巧：如果是数出来的，很可能是离散数据；如果是测量出来的，那就是连续数据。
4. Population, Sample, and Census | 总体、样本与普查
When you study a group, the population is the whole group you want information about. For instance, all Year 7 students in your school. A sample is a smaller group chosen from the population. A census is when you collect data from every single member of the population. A sample is usually easier and quicker, but if it is not chosen carefully, it may not represent the whole population perfectly.
当你研究一个群体时，总体是你想要了解信息的整个群体。例如，你们学校所有七年级学生。样本是从总体中选出的较小群体。普查是指从总体的每一个成员那里收集数据。样本通常更容易、更快捷，但如果选择不慎，可能无法完美代表整个总体。
Key term: Bias. If a sample is not chosen fairly, it can lead to incorrect conclusions about the population.
关键术语：偏差。如果样本选择不公平，可能导致关于总体的错误结论。
5. Frequency and Tally Charts | 频数与计数符号表
Frequency means how often something occurs. A frequency table shows categories or values along with their frequencies. To make counting easier, we use tally marks. A tally is a short stroke used to count items; every fifth stroke is drawn diagonally across the previous four to make a group of five. The tally column helps you count without missing any item.
频数表示某事发生的次数。频数表显示各个类别或数值及其频数。为了更方便计数，我们使用计数符号。计数符号是用来计数的短竖线；每五个为一组，第五条线斜着画过前四条竖线，形成一个“五条一组”的标记。计数符号栏帮助你计数而不遗漏任何项目。
- Red cars: |||| (4)
- Blue cars: |||| || (7)
- White cars: |||| |||| (10)
- 红色汽车：|||| (4)
- 蓝色汽车：|||| || (7)
- 白色汽车：|||| |||| (10)
Always use a key if your tally chart might be unclear. Counting systematically with tallies is an essential skill for data handling.
如果计数符号表可能不清晰，一定要使用图例。有系统地用计数符号计数是数据处理的基本技能。
6. Averages: Mean, Median, and Mode | 平均数：均值、中位数和众数
An average is a value that represents the centre of a set of data. The three main averages are mean, median, and mode. The mean is found by adding all the values and then dividing by the number of values. The formula is shown below.
平均数是代表一组数据中心的值。三个主要的平均数是均值、中位数和众数。均值通过将所有数值相加再除以数值的个数得到。公式如下所示。
Mean = Σxᵢ ÷ n
The median is the middle value when the data is ordered from smallest to largest. If there are two middle numbers, find their mean. The mode is the value that appears most often. A data set can have one mode, more than one mode (called bimodal or multimodal), or no mode at all.
中位数是将数据从小到大排序后位于中间的值。如果有两个中间的数，就求它们的均值。众数是出现次数最多的值。一组数据可以有一个众数、多个众数（称为双众数或多众数），或者根本没有众数。
In exam questions, you will be asked to calculate these, so make sure you know the difference between them.
在考试题目中，会要求你计算这些值，因此务必清楚它们之间的区别。
7. Range and Spread | 极差与离散程度
The range tells us how spread out the data is. It is the simplest measure of variation. The range is the difference between the largest and smallest values.
极差告诉我们数据的分散程度。它是最简单的离散程度度量。极差是最大值与最小值之间的差。
Range = Max − Min
A small range means the data values are close together; a large range means they are more spread out and varied. The range is not an average, but it is often used together with the mean or median to describe a data set.
极差小意味着数据值很接近；极差大意味着数据更加分散和多样化。极差不是平均数，但它常与均值或中位数一起用来描述一组数据。
8. Graphs and Charts: Bar Charts, Pictograms, Pie Charts | 图表：条形图、象形图、饼图
To present data clearly, we use different types of chart. A bar chart uses rectangular bars of equal width. The height of each bar represents the frequency. Bar charts are excellent for comparing categories. A pictogram uses small pictures or symbols to represent data. Each picture stands for a certain number of items, and a key explains the scale. A pie chart (or circle graph) shows proportions of a whole. The entire circle represents the total, and each slice shows a category as part of that total. Pie charts are drawn by calculating angles.
为了清晰地展示数据，我们使用不同类型的图表。条形图使用等宽的长条，每个长条的高度代表频数。条形图非常适合比较各类别。象形图使用小图片或符号来代表数据。每个图片代表一定数量的物品，图例说明比例。饼图（或圆形图）显示整体中的比例。整个圆代表总数，每个扇形代表一个类别占总数的比例。饼图通过计算角度来绘制。
In Year 7, you need to be able to read and interpret these charts, and sometimes draw them yourself. Always label your axes, include a title, and pay attention to the scale.
在七年级，你需要能够阅读和解释这些图表，有时还需要自己绘制。始终标注坐标轴、添加标题，并注意比例尺。
9. Probability: Likelihood Scale and Events | 概率：可能性量表和事件
Probability is the study of chance. It describes how likely an event is to happen. The probability of an impossible event is 0, and the probability of a certain event is 1. Probabilities can be written as fractions, decimals, or percentages. On the likelihood scale, we
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