Year 9 CCEA Statistics: Vocabulary Terms Memorisation Guide | 9年级CCEA统计学术语速记指南

📚 Year 9 CCEA Statistics: Vocabulary Terms Memorisation Guide | 9年级CCEA统计学术语速记指南

Whether you are starting your first statistics topic or revising for an end-of-year test, knowing the correct vocabulary is half the battle. For Year 9 students following the CCEA specification, every question on charts, averages or probability expects you to use precise statistical language. This guide groups all the key terms into logical categories, explains each one in clear English and Chinese, and adds memory shortcuts so that tricky words like ‘stratified sample’ or ‘interquartile range’ finally stick. Work through the sections and then use the quick hacks at the end to lock them into long-term memory.

无论你是刚开始学习统计学的第一个专题，还是正在为期末考试复习，掌握正确的词汇都是成功的一半。对于遵循CCEA课程的九年级学生来说，每一道关于图表、平均数或概率的题目都要求你使用精确的统计语言。本指南将所有关键术语按逻辑分组，用清晰的英文和中文逐一解释，并配上记忆捷径，让“分层样本”或“四分位距”这类难记的词最终牢牢记住。依次学习各节，最后利用文末的快速记忆技巧将它们刻入长期记忆。

1. Data Collection Foundations | 数据收集基础

Every statistical investigation starts with gathering information. The four words below describe where your data comes from and how much of the whole group you actually study. Getting these right prevents confusion when a question asks you to decide between a census and a sample survey.

每项统计调查都从收集信息开始。下面的四个词描述数据的来源以及你实际研究了整个群体中的多少。当题目要求你在普查和抽样调查之间做选择时，正确理解这些术语可以避免混淆。

Population – the complete set of people, animals, objects or events that you are interested in. For example, if you want to know the favourite sport of Year 9 students in your school, the population is every Year 9 student in that school.

总体 – 你感兴趣的全部人、动物、物品或事件的集合。例如，如果你想知道你所在学校九年级学生最喜欢的运动，总体就是那所学校所有的九年级学生。

Sample – a smaller part of the population that you actually collect data from. It should be representative so that the results can be generalised. Asking 50 Year 9 students from different form classes creates a sample of the larger population.

样本 – 你实际从中收集数据的那部分总体。样本应当具有代表性，这样结果才能被推广。从不同班级里选出50名九年级学生就构成了更大总体的一个样本。

Census – a survey that collects data from every single member of the population. It gives the most accurate picture but is often too expensive or time-consuming for large populations.

普查 – 从总体中每一个成员都收集数据的调查。它能提供最准确的画卷，但对于大总体来说往往成本太高或太耗时。

Survey – the general method of asking questions and recording responses. A survey can be carried out as a census (everyone) or using a sample (some people).

调查 – 通过提问并记录回答来收集数据的通用方法。调查可以以普查（所有人）的形式进行，也可以用样本（部分人）的形式进行。

Memory tip: Think ‘Sample is a Slice’ – only a piece of the whole pizza. Census starts with C, like ‘Complete’.

记忆技巧：把样本想象成“一片切片”，只是整个比萨的一部分。普查的“普”有“普遍、全面”的含义。

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2. Types of Data | 数据的类型

Data can be described by its nature (words or numbers) and by the way it is measured. Knowing whether your data is discrete or continuous helps you choose the right graph and decide how to calculate averages.

数据可以通过它的性质（文字还是数字）以及测量方式来描述。知道数据是离散的还是连续的，能帮助你选择合适的图表并决定如何计算平均值。

Qualitative (categorical) data – non‑numerical information that describes a quality or category. Examples: hair colour, type of car, favourite subject. These are often shown in bar charts or pie charts.

定性（分类）数据 – 描述性质或类别的非数字信息。例如：头发颜色、汽车类型、最喜欢的科目。这类数据常用条形图或饼状图展示。

Quantitative data – numerical information that measures or counts something. It can be split further into discrete and continuous.

定量数据 – 用来衡量或计数的数值信息。它可进一步分为离散数据和连续数据。

Discrete data – quantitative data that can only take specific, separate values. Usually you count it in whole numbers. Examples: number of pets, number of goals scored, shoe size (even though it has halves, it takes fixed step sizes).

离散数据 – 只能取特定、分离值的定量数据。通常用整数计数。例如：宠物数量、进球数、鞋码（尽管鞋码有半码，但仍然是固定的步长）。

Continuous data – quantitative data that can take any value within a given range. You measure it rather than count it. Examples: height, mass, time taken to run 100 m, temperature.

连续数据 – 在给定范围内可取任意值的定量数据。你是测量它而不是计数它。例如：身高、质量、百米跑用时、温度。

Primary data – information you collect yourself for the specific purpose of your investigation. Conducting your own traffic count is primary data.

原始数据 – 你为自己的调查目的亲自收集的信息。自己进行交通流量计数就属于原始数据。

Secondary data – information that already exists, collected by someone else for a different purpose. Using a government website to find population figures is secondary data.

二手数据 – 已经存在的、由他人为不同目的收集的信息。使用政府网站查找人口数字就是二手数据。

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3. Graphs and Charts | 图形与图表

CCEA questions regularly ask you to identify the correct type of diagram for a given data set or to interpret one that is already drawn. The differences between a bar chart, histogram and scatter graph are especially important.

CCEA的题目经常要求你为给定的数据集选择正确的图表类型，或者解读已经画好的图表。条形图、直方图和散点图之间的区别尤为重要。

Bar chart – uses rectangular bars of equal width with gaps between them. Each bar represents the frequency of a category. Used for qualitative data or discrete data displayed as categories.

条形图 – 使用等宽的矩形条，条与条之间有间隙。每个条形表示一个类别的频数。用于定性数据或按类别显示的离散数据。

Pictogram – a chart where a small icon or symbol represents a fixed number of items. A key tells you the value of one symbol; part‑symbols show fractions of that value.

象形图 – 用一个小图标或符号表示固定数量项目的图表。图例会告诉你一个符号代表多少数值；不完整的符号表示分数部分。

Pie chart – a circle divided into sectors. Each sector’s angle is proportional to the frequency of the category it represents. To find the angle, multiply the fraction by 360°.

饼状图 – 分成若干扇形的圆。每个扇形的角度与它所代表的类别的频数成正比。计算角度时，用各部分的分数乘以360°。

Line graph – data points plotted and joined with straight lines. Usually used to show changes over time (time‑series). The gradient indicates the rate of change.

折线图 – 将数据点描出并用直线连接。通常用来显示随时间变化的情况（时间序列）。斜率表示变化率。

Scatter graph (scatter plot) – plots two sets of continuous data on an x‑y axis. Each point represents a pair of values. Used to look for correlation or relationships.

散点图 – 在x‑y坐标轴上绘制两组连续数据。每个点代表一对数值。用来寻找相关性或关系。

Histogram – drawn for grouped continuous data. The bars touch, showing that the data is continuous. The area of each bar is proportional to the frequency; if class widths are equal, height also represents frequency.

直方图 – 用于分组连续数据。长条紧靠在一起，表示数据是连续的。每个条的面积与频数成正比；如果组距宽度相等，高度也可代表频数。

Frequency polygon – a line formed by joining the midpoints of the tops of histogram bars with straight lines. Often helps compare two distributions on the same axes.

频数多边形 – 将直方图各条顶部中点用直线连接形成的折线。常用于在同一坐标轴上比较两个分布。

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4. Measures of Central Tendency | 集中趋势的度量

Averages summarise a whole data set with one representative number. You must know not only how to calculate the mean, median and mode but also when each is most appropriate.

平均数用一个代表性数字概括整个数据集。你不仅要会计算平均数、中位数和众数，还要知道各自最适合在什么时候使用。

Mean – the arithmetic average. Add all the values together and divide by how many values there are.

平均数 – 算术平均值。将所有数值相加，再除以数值的总个数。

Mean = Σx ÷ n or for a frequency table Mean = Σfx ÷ Σf

Advantage: uses every piece of data. Disadvantage: affected by extreme values (outliers).

优点：使用了每一个数据。 缺点：受极端值（异常值）影响大。

Median – the middle value when the data are written in order. For n numbers, the position is (n+1)/2 th value.

中位数 – 将数据按大小顺序排列后位于中间的值。对于n个数，位置为第 (n+1)/2 个。

Advantage: not affected by outliers, so it is better for skewed data like house prices or incomes.

优点：不受异常值影响，因此对于房价或收入这样的偏态数据更好。

Mode – the value that appears most often. A data set can have one mode, more than one mode (bimodal) or no mode at all.

众数 – 出现次数最多的值。一组数据可以有一个众数、多个众数（双众数）或根本没有众数。

Modal class – in grouped data, the class interval with the highest frequency. You cannot find the exact mode from a grouped table, only the modal group.

众数组 – 在分组数据中，频数最高的那个组距。从分组表中只能找到众数所在的组，无法得出精确的众数。

Memory hook: Mean is the one that ‘means’ calculation; Median remembers ‘middle’; Mode sounds like ‘most’.

记忆挂钩：Mean（平均数）需要“mean”（刻薄地）计算；Median（中位数）联想到“中间”；Mode（众数）读音像“most”（最多）。

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5. Measures of Spread | 离散程度的度量

Averages alone can be misleading – two classes might have the same mean test score but very different spreads of marks. Measures of spread tell you how consistent or varied the data are.

仅有平均数可能会产生误导——两个班级的考试平均分可能相同，但分数的离散程度可能完全不同。离散程度的度量告诉你数据是多么一致或多么分散。

Range – the simplest measure of spread: Range = Largest value – Smallest value. It is quick to find but only uses two data points, so one outlier can make it huge.

极差 – 衡量离散程度最简单的方法：极差 = 最大值 – 最小值。它容易求出，但只用了两个数据点，一个异常值就可能使它变得极大。

Lower quartile (Q₁) – the median of the lower half of the data (first 25%). It splits off the bottom quarter.

下四分位数 (Q₁) – 数据下半部分（前25%）的中位数。它切掉了最底部的四分之一。

Upper quartile (Q₃) – the median of the upper half of the data (top 25%).

上四分位数 (Q₃) – 数据上半部分（最高的25%）的中位数。

Interquartile range (IQR) – the

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