SQA Year 9 Statistics: Quick-Reference Terminology Guide | SQA 九年级统计：词汇术语速记指南

📚 SQA Year 9 Statistics: Quick-Reference Terminology Guide | SQA 九年级统计：词汇术语速记指南

Welcome to your essential revision companion for SQA Year 9 Statistics. Mastering the language of data is half the battle – this bilingual guide breaks down every key term you need, with memory shortcuts and real examples that make the definitions stick. Whether you are preparing for a class test or building foundations for National 5, these concise explanations will strengthen your statistical vocabulary and boost your confidence.

欢迎使用 SQA 九年级统计必备复习指南。掌握数据的语言是成功的一半——这份双语对照手册拆解了你需要掌握的每一个关键术语，搭配记忆诀窍和真实示例，让定义不再遗忘。无论你是在准备课堂测验，还是为 National 5 打基础，这些精炼的解释都将强化你的统计词汇，提升你的信心。

1. What is Statistics? | 什么是统计学？

Statistics is the science of collecting, organising, analysing, and interpreting numerical information. At Year 9 level, you will learn to describe data sets, calculate summaries, and draw simple conclusions – the first steps towards making evidence-based decisions in everyday life and further study.

统计学是收集、整理、分析和解读数字信息的科学。在九年级阶段，你将学习描述数据集、计算汇总量并得出简单结论——这是走向日常生活和更高阶学习中进行循证决策的第一步。

2. Types of Data | 数据类型

Data can be qualitative (descriptive, non-numerical) or quantitative (numerical). Quantitative data splits further into discrete (countable values, like number of siblings) and continuous (measurements, like height or time). Recognising the data type helps you choose the right chart or summary statistic.

数据可以是定性数据（描述性、非数值）或定量数据（数值型）。定量数据又分为离散数据（可数数值，如兄弟姐妹数量）和连续数据（测量值，如身高或时间）。识别数据类型有助于选择合适的图表或汇总统计量。

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

The three main averages are mean (sum of values ÷ number of values, written as x̄), median (the middle value when ordered), and mode (the most frequent value). For the data set 3, 5, 5, 7, 9: mean = 5.8, median = 5, mode = 5. Use the mean for symmetric data, the median when outliers are present, and the mode for categorical summaries.

三个主要的平均数是平均数（总和 ÷ 数值个数，记作 x̄）、中位数（排序后中间的值）和众数（出现频率最高的值）。对于数据集 3, 5, 5, 7, 9：平均数 = 5.8，中位数 = 5，众数 = 5。对称数据用平均数，有异常值时用中位数，分类汇总用众数。

4. Measures of Spread | 离散程度的度量

Spread tells you how tightly or widely the data points cluster. Key measures are range (max – min), interquartile range (IQR) (Q3 – Q1, the middle 50%), and standard deviation (a measure of average distance from the mean, symbol σ or s). A smaller IQR or standard deviation means more consistency.

离散程度告诉你数据点聚集得紧密还是分散。关键度量有极差（最大值 – 最小值）、四分位距 (IQR)（上四分位数 Q3 – 下四分位数 Q1，覆盖中间 50% 的数据）和标准差（数据与平均数之间距离的平均度量，符号 σ 或 s）。四分位距或标准差越小，说明越一致。

5. Five-Number Summary & Box Plots | 五数概括与箱线图

A five-number summary consists of minimum, Q1 (lower quartile), median (Q2), Q3 (upper quartile), and maximum. These five values are used to draw a box plot: the box spans IQR with a line at the median, and whiskers extend to the min and max (within 1.5 × IQR). Box plots make comparisons between groups easy.

五数概括包括最小值、下四分位数 Q1、中位数 Q2、上四分位数 Q3 和最大值。这五个数值用于绘制箱线图：箱体覆盖四分位距，中间标记中位数；须线延伸至最小值和最大值（通常限制在 1.5 × IQR 内）。箱线图便于组间比较。

6. Frequency Distributions & Histograms | 频率分布与直方图

A frequency table lists data values or intervals alongside their counts. A histogram uses adjacent bars whose area is proportional to frequency – for equal-width intervals, bar height equals frequency. Key terms: class interval, class width, and frequency density (frequency ÷ class width), which is essential for unequal intervals.

频率表列出数据值或区间及其频数。直方图使用相邻的长条，其面积与频数成正比——对于等宽度区间，条形高度等于频数。关键术语：组距、组宽和频率密度（频数 ÷ 组宽），在区间不等宽时必须使用频率密度。

7. Charts for Categorical Data | 分类数据的图表

Common visuals include bar charts (separate bars for categories, height = frequency or percentage), pictograms (icons representing units, always supply a key), and pie charts (sectors proportional to category size, calculated as (category frequency ÷ total) × 360°). Always label axes and include a title.

常见可视化图表包括条形图（不同类别用独立长条，高度 = 频数或百分比）、象形图（用图标代表单位，必须附上图例）和饼图（扇形大小与类别大小成比例，计算公式为 (类别频数 ÷ 总数) × 360°）。记得标注坐标轴并添加标题。

8. Scatter Graphs & Correlation | 散点图与相关性

A scatter graph displays paired numerical data to reveal relationships. Correlation describes the direction and strength of a linear pattern: positive (both increase), negative (one increases as the other decreases), or no correlation. Line of best fit (or trend line) helps make predictions, with observations noted as ‘outliers’ if far from the pattern.

散点图展示成对的数值数据以揭示关系。相关性描述线性模式的方向和强度：正相关（两者同时增加）、负相关（一个增加时另一个减少）或无相关。最佳拟合线（趋势线）用于预测，远离模式的点被称为“异常值”。

9. Probability Language & Scale | 概率语言与标度

Probability measures how likely an event is, on a scale from 0 (impossible) to 1 (certain). Terms like equally likely, likely, unlikely, and even chance (probability = 0.5) are tested. The sample space is the set of all possible outcomes, and a probability of an event is (favourable outcomes) ÷ (total outcomes) when all outcomes are equally likely.

概率衡量一个事件发生的可能性，标度从 0（不可能）到 1（必然发生）。考试会涉及等可能、很可能、不太可能和相等机会（概率 = 0.5）等术语。样本空间是所有可能结果的集合。当所有结果等可能时，事件的概率 =（有利结果数）÷（总结果数）。

10. Sampling & Bias | 抽样与偏差

When collecting data, a population is the whole group; a sample is a subset. A random sample gives every member an equal chance, helping to avoid bias. An unbiased sample is representative. Terms to know: response bias, leading question, and small sample effect can all distort conclusions.

收集数据时，总体是整个群体；样本是其中的一个子集。随机样本让每个成员被抽到的概率相等，有助于避免偏差。无偏差的样本具有代表性。需要知道的术语：应答偏差、诱导性问题和小样本效应都可能扭曲结论。

11. Memory Shortcuts for Key Terms | 关键术语记忆捷径

Link tricky vocabulary to visual hooks: mean = ‘mean teacher adds everyone’s grade then divides’ (sum ÷ count). Median = ‘middle lane of a highway’ – imagine the sorted data as cars, the median is the one exactly in the middle. Mode = ‘most often’ (both start with ‘mo’). For IQR, think ‘Inter – Quarter – Range’, the gap between the quarter marks. Create a chant: Q1 – Q2 – Q3, like a three-part chorus.

把难记的词汇与形象挂钩联系起来：平均数——“平均”就像平均分配，总和除以个数。中位数——“中间”的数据。众数——“众多”出现的数字。对于 IQR（四分位距），记住“四分之一间的距离”。读成 Q1 – Q2 – Q3，像三段式旋律。

12. Quick Self-Test & Final Tips | 快速自测与最后提示

Cover the translations, say the term aloud, then check. Flash cards work well: write ‘Variance’ on one side, ‘σ² or s²’ on the other. In the exam, underline command words like ‘calculate’, ‘compare’, or ‘justify’ to know what angle to take. Always round answers sensibly and label units. Practise reading box plots and histograms without hesitation – these visuals are guaranteed to appear.

遮住翻译，大声说出术语，然后核对。制作抽认卡：正面写“方差”，反面写“σ² 或 s²”。考试时，在“计算”“比较”“说明理由”等指令词下划线，以明确答题方向。始终合理四舍五入并标注单位。要能毫不犹豫地解读箱线图和直方图——这些图表几乎逢考必出。

Published by TutorHao | SQA Year 9 Statistics Revision Series | aleveler.com

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