📚 Year 9 CIE Statistics: Key Vocabulary Quick Revision Guide | Year 9 CIE 统计：词汇术语速记指南
Mastering the language of statistics is the first step to thinking like a data detective. This guide brings together the essential terms you will meet in Year 9 CIE Statistics – from types of data to probability – and presents them in clear English-Chinese pairs with quick memory tricks. Use it to revise, self‑test or simply build confidence in reading statistical questions.
掌握统计学的语言是像数据侦探一样思考的第一步。本指南汇集了你在 Year 9 CIE 统计中会遇到的核心术语——从数据类型到概率——并用清晰的中英对照和速记窍门呈现。你可以用它来复习、自测，或者只是建立理解统计题目的信心。
1. Types of Data | 数据类型
Categorical data (also called qualitative data) describes qualities, labels or groups. The values are not numbers but categories. Examples: favourite colour, types of pet, 'yes' or 'no' answers in a survey.
分类数据（也称作定性数据）描述品质、标签或组别。它的值不是数字而是类别。例如：最喜欢的颜色、宠物类型、调查中的“是”或“否”回答。
Numerical data (quantitative data) is information that can be measured or counted and is expressed as numbers. It can be further split into discrete and continuous data.
数值数据（定量数据）是可以被测量或计数的信息，用数字表示。它可以进一步分为离散数据和连续数据。
Discrete data can only take specific, separate values – there are gaps between the possible numbers. It often comes from counting. Examples: number of students in a class, goals scored in a match, shoe sizes (only certain sizes exist).
离散数据只能取特定的、分离的值——可能数字之间存在间隙。它通常来自计数。例如：班级里的学生人数、一场比赛的进球数、鞋码（只有特定尺码存在）。
Continuous data can take any value within a given range. The values are connected without jumps and usually come from measuring instruments. Examples: height, mass, temperature, time taken to run 100 metres.
连续数据可以在给定范围内取任意值。这些值是连续无跳跃的，通常来自测量仪器。例如：身高、质量、温度、跑100米所用的时间。
💡 Quick memory link: Discrete means 'distinct and separate' – you can count discrete items one by one. Continuous sounds like 'continue', so the data keeps going without a break.
💡 快速记忆联想：离散意味着“不连续、分开的”——你可以一个个数出来。连续听起来像“持续”，表示数据不间断地延伸。
2. Collecting Data | 数据收集
Population refers to the entire set of individuals or items that we want to study. If you ask every member of the population, you carry out a census.
总体是指我们想要研究的全部个体或项目的集合。如果你询问了总体中的每一个成员，你就是在进行普查。
Sample is a smaller, manageable subset of the population selected to represent the whole group. Taking a sample is often quicker and cheaper than a census.
样本是从总体中选出的一个较小且易于处理的子集，用来代表整个群体。抽取样本通常比普查更快捷、更经济。
Bias happens when a sample or survey method systematically over‑represents or under‑represents certain parts of the population, leading to misleading conclusions. For example, asking only your friends about school lunches may not reflect the whole school.
偏倚发生在样本或调查方法系统性地过多或过少代表了总体中的某些部分，从而导致误导性结论。例如，只问你自己的朋友关于学校午餐的看法可能无法反映全校情况。
Primary data is collected first‑hand by the researcher for a specific purpose. Secondary data is data that already exists and was collected by someone else (e.g., internet databases, government reports).
一手数据是研究者为了特定目的亲自收集的数据。二手数据是已经存在、由他人收集的数据（如网络数据库、政府报告）。
💡 Word clue: 'Sample' is a small taste of the whole, just like a food sample. 'Census' covers the whole cake!
💡 词语线索：“样本”就像一小份品尝样，而“普查”覆盖了整个蛋糕！
3. Averages: Mean, Median, Mode | 平均数、中位数、众数
Mean is the sum of all data values divided by the number of values. It is the most common measure of average but can be affected by extreme values.
平均数是所有数据值的总和除以数据的个数。它是表示平均的最常用度量，但容易受极端值影响。
Mean = (Sum of all values) ÷ (Number of values)
平均数 = 数值总和 ÷ 数值个数
Median is the middle value when the data is arranged in order. If there are two middle numbers, the median is the mean of those two. The median is not affected by very large or small outliers.
中位数是将数据按顺序排列后处于中间位置的值。如果有两个中间数，则中位数是这两个数的平均数。中位数不受非常大或非常小的异常值影响。
Mode is the value that appears most often in a data set. A set of data can have one mode, more than one mode (bimodal or multimodal), or no mode at all.
众数是数据集中出现次数最多的值。一组数据可以有一个众数、多于一个众数（双众数或多众数），或者根本就没有众数。
💡 Remember: Mean is the 'average' you use most in daily life – add and divide. Median is the middle – think of the median strip on a road. Mode begins with 'mo' as in 'most'!
💡 速记：平均数是日常最常用的平均——先加后除。中位数是中间——想象马路中央的隔离带（median strip）。众数的“众”表示最多人穿的款式，所以是最常见的值。
4. Range and Spread | 极差与离散程度
Range is the difference between the largest and the smallest values in a data set. It gives a quick idea of how spread out the data is.
极差是数据集中最大值与最小值之间的差值。它能快速反映数据的离散程度。
Range = Maximum value – Minimum value
极差 = 最大值 − 最小值
A small range means the data points are consistent and close together. A large range suggests high variability or the presence of outliers.
极差小说明数据点一致且聚集在一起。极差大则暗示变异性高或者存在异常值。
The range is simple to calculate but only uses the two extreme values, so it can be influenced by a single outlier.
极差计算简单，但只使用了两个最极端的值，因此容易受单个异常值的影响。
💡 Memory hook: 'Range' sounds like 'mountain range' – the distance from the lowest valley to the highest peak!
💡 联想记忆：“极差”就像测量山脉从最低谷到最高峰的距离！
5. Frequency Tables | 频数表
A frequency table lists each data value or category together with its frequency – how many times it occurs. It helps organise raw data into a compact summary.
频数表将每个数据值或类别连同它的频数（出现的次数）一起列出。它有助于将原始数据整理成一个紧凑的摘要。
A tally is a quick counting method where each observation is marked with a stroke, and every fifth stroke is drawn diagonally across the previous four to make groups of five (||||). This makes counting frequencies easier and less error‑prone.
划记是一种快速计数方法，每观察到一次就划一道，每第五道斜向划在前四道上形成五道一组（||||）。这样便于数出频数，减少错误。
When data covers a large range, we can group values into class intervals and build a grouped frequency table. The interval that has the highest frequency is called the modal class.
当数据覆盖的范围很大时，我们可以将数值归入组区间，制作分组频数表。频数最高的那个区间称为众数组。
💡 Visual tip: Tally strokes look like a gate – '5‑bar gate'. Each complete gate represents 5, making counting fast.
💡 视觉提示：划记笔画像栅栏门，“正”字的五笔也恰好是5，数起来很快。
6. Bar Charts and Pictograms | 条形图和象形图
A bar chart uses rectangular bars to show frequencies or values for different categories. The height (or length, for horizontal bars) of each bar represents the frequency. Bars must have equal width and there should be gaps between them to show that the categories are separate.
条形图用矩形条来展示不同类别的频数或数值。每根条的高度（或水平条的长度）代表频数。条形的宽度必须均等，而且条形之间要有空隙，表明类别是独立的。
A pictogram uses small icons or symbols to represent data. Each symbol stands for a certain number of items, and a key must be provided to show what one symbol represents. Part of a symbol can be used for fractions of the amount.
象形图用小图标或符号来呈现数据。每个符号代表一定数量的项目，必须提供图例说明每个符号代表的数值。可以使用符号的一部分来表示分数。
Both charts should always include a clear title and labelled axes (where relevant) and a suitable scale so the chart is easy to read.
两种图表都应该包含清晰的标题、标注好的坐标轴（如果适用）和合适的刻度，以便图表易于阅读。
💡 Compare: Bar chart – bars stand apart like talking faces in a crowd. Pictogram – pictures tell a story without words.
💡 对比：条形图 – 条形如人群中各自独立的说话面孔；象形图 – 图形不需文字就能讲故事。
7. Pie Charts | 饼图
A pie chart is a circular chart divided into sectors (slices). Each sector represents a category, and the angle (and area) of the sector is proportional to the frequency of that category.
饼图是一种按扇形（切片）划分的圆形图表。每个扇形代表一个类别，扇形的角度（和面积）与该类别的频数成正比。
The central angle for a sector is calculated using the formula:
Angle = (Frequency of category ÷ Total frequency) × 360°
扇形的圆心角计算公式为：
角度 = （类别频数 ÷ 总频数）× 360°
Pie charts are best used when you have a moderate number of categories (usually fewer than six) and your data adds up to a meaningful whole. They make it easy to compare parts of a whole at a glance.
饼图最适合有适量类别（通常少于六个）且数据加起来构成一个有意义的整体的情况。它们能让人一眼就看出各部分在整体中的占比。
💡 Construction tip: Always start measuring angles from a fixed line (e.g., a vertical radius) and work your way around. Label each sector clearly or provide a legend.
💡 绘制窍门：总是从一条固定线（例如从竖直半径）开始并依次测量角度。清楚地给每个扇形加标签或提供图例。
8. Line Graphs and Time Series | 折线图与时间序列
A line graph shows how data changes over time. Points are plotted and then connected by straight line segments. The horizontal axis usually shows time or ordered categories, while the vertical axis shows the measured variable.
折线图展示数据如何随时间变化。先标出数据点，再用直线段连接。横轴通常表示时间或有序类别，纵轴表示测量的变量。 Published by TutorHao | Year 9 统计 Revision Series | aleveler.com
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