📚 Year 7 CIE Statistics: Quick Guide to Key Vocabulary Terms | Year 7 CIE 统计：核心词汇速记指南
Welcome to your Year 7 CIE Statistics journey. Mastering the subject starts with a solid grip on the terminology. This guide walks you through every key term you need, pairing clear English explanations with Chinese translations and memory tips to help you learn faster and retain longer.
欢迎开启 Year 7 CIE 统计学习之旅。掌握这门学科的第一步就是牢牢抓住术语。本指南将带你梳理每一个必会关键词汇，用清晰的英文解释搭配中文翻译和记忆锦囊，帮你学得更快、记得更牢。
1. Data and Types of Data | 数据及其类型
Data is a collection of facts, numbers, or observations. We classify data into qualitative (descriptions) and quantitative (numbers). Quantitative data can be discrete, taking only specific values, or continuous, taking any value in a range.
数据是事实、数字或观察结果的集合。我们将数据分为定性数据（描述性）和定量数据（数字型）。定量数据可以是离散的，只能取特定值；也可以是连续的，可以取一个范围内的任意值。
Discrete data often comes from counting. Ask yourself ‘Can it be counted?’ For example, the number of students in a class is discrete – you cannot have 28.5 students.
离散数据通常来自计数。问自己“可以数出来吗？”例如，班上学生人数是离散的——你不可能有 28.5 个学生。
Continuous data comes from measuring. Ask ‘Can it be measured?’ Height, weight and temperature are continuous because they can take any value between two numbers, limited only by your measuring tool.
连续数据来自测量。问自己“可以测量吗？”身高、体重和温度都是连续的，因为它们可以取两个数值之间的任何值，只受测量工具精度的限制。
| Data Type 数据类型 | Example 示例 | Memory Tip 记忆点 |
| Qualitative 定性 | Eye colour, favourite sport | Think ‘quality’ = describes a quality. |
| Quantitative discrete 定量离散 | Shoe size, number of siblings | ‘Counting’ – no fractions allowed. |
| Quantitative continuous 定量连续 | Height in cm, time in seconds | ‘Measuring’ – any value possible. |
2. Collecting Data: Population, Sample and Survey | 收集数据：总体、样本与调查
When we collect data, the population means the whole group we want to know about. A sample is a smaller group chosen from the population. A survey is the method of asking questions to gather data.
当我们收集数据时，总体是指我们想了解的整个群体。样本是从总体中选出的一个较小群体。调查是通过提问来收集数据的方法。
A census is when data is collected from every member of the population. A sample is used because asking everyone is often too time-consuming or expensive.
普查是从总体中的每一个成员收集数据。使用样本是因为询问每个人通常太耗时或太昂贵。
Remember: ‘Population = P for Perfectly everyone, Sample = S for a Slice of the pie.’ Think of a pizza – the whole pizza is the population, one slice is the sample.
记住：“Population 的 P 代表 全部 (Perfectly everyone)，Sample 的 S 代表 一片 (Slice)。”想象一个披萨——整个披萨是总体，一块披萨就是样本。
3. Organising Data: Frequency and Tally | 整理数据：频数与记数
After collecting raw data, we organise it using a frequency table. The frequency is the number of times something occurs. A tally is a quick way of counting using marks grouped in fives.
收集原始数据后，我们用频数表来整理数据。频数是某事物出现的次数。记数是使用以五为一组的记号来快速计数的方法。
Tally marks: each vertical line counts one, and the fifth line crosses the previous four. So |||| represents 4, and |||| represents 5. This makes totals easy to read.
记数标记：每条竖线计一个，第五条线斜穿前四个。所以 |||| 表示 4，而 |||| 表示 5。这样总计一目了然。
Tip: Tally rhymes with ‘ally’ – your ally in keeping count without mistakes.
小窍门：Tally 和 “tally-ho” 一样都有快速计数的意思，是你的计数好帮手，避免出错。
4. Measures of Central Tendency: Mean | 集中趋势量度：均值（平均数）
The mean is what most people call the average. It is found by summing all the values and dividing by the number of values. The formula is:
均值就是大多数人所说的平均数。计算方法是将所有数值相加，再除以数值的个数。公式为：
Mean = (Sum of all data values) ÷ (Number of values)
均值 = (所有数据值之和) ÷ (数据值的个数)
For example, the mean of 3, 7 and 8 is (3+7+8) ÷ 3 = 18 ÷ 3 = 6. Think of the mean as sharing equally – if three friends have 3, 7 and 8 sweets, sharing equally gives each person 6.
例如，3、7 和 8 的均值是 (3+7+8) ÷ 3 = 18 ÷ 3 = 6。把均值想象成平均分配——如果三个朋友分别有 3 块、7 块和 8 块糖，平均分配后每人得到 6 块。
The mean works well when there are no extreme outliers. A single very high or very low value can pull the mean away from the centre.
当没有极端异常值时，均值效果很好。一个极高或极低的值会把均值拉离中心。
5. Measures of Central Tendency: Median and Mode | 集中趋势量度：中位数与众数
The median is the middle value when the data is ordered from smallest to largest. If there is an even number of values, the median is the mean of the two middle numbers.
中位数是数据从小到大排序后位于中间的值。如果数值个数是偶数，中位数就是中间两个数的均值。
For 3, 7, 8, the median is 7. For 2, 4, 6, 8, the median is (4+6) ÷ 2 = 5. The median is not affected by outliers – it stays firmly in the middle.
对于 3、7、8，中位数是 7。对于 2、4、6、8，中位数是 (4+6) ÷ 2 = 5。中位数不受异常值影响，始终稳居中间。
The mode is the value that appears most often. A data set can have one mode, more than one mode (bimodal), or no mode at all.
众数是出现次数最多的值。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。
Memory aid: ‘Median sounds like medium – the one in the middle. Mode sounds like most – the one that appears most.’
记忆法：“Median 听起来像 medium（中间的），即中间那个；Mode 听起来像 most（最多），即出现最多的那个。”
6. Range: Measure of Spread | 极差：离散程度的量度
The range tells us how spread out the data is. It is the difference between the largest value and the smallest value. Formula:
极差告诉我们数据的分散程度。它是最大值与最小值的差。公式：
Range = Largest value − Smallest value
极差 = 最大值 − 最小值
For the set 3, 7, 8, 12, the range is 12 − 3 = 9. A small range means the data is closely grouped; a large range means data is more spread.
对于数据集 3、7、8、12，极差为 12 − 3 = 9。极差小意味着数据比较集中；极差大意味着数据比较分散。
Think of the range as the ‘stretch’ from the lowest to the highest – like the wingspan of a bird.
把极差想象成从最低点到最高点的“跨度”——就像鸟的翼展。
7. Bar Charts | 条形图
A bar chart represents data using rectangular bars of equal width. The height (or length) of each bar shows the frequency. Bars do not touch, because the categories are separate.
条形图使用宽度相等的长方形条来表示数据。每个条的高度（或长度）显示频数。条形之间不接触，因为各类别是独立的。
Axes must be labelled: the horizontal axis shows categories (like colours or subjects), the vertical axis shows frequency. Always give your chart a title.
坐标轴必须标记：横轴显示类别（如颜色或科目），纵轴显示频数。务必给图表加上标题。
Use bar charts for discrete or categorical data. They are different from histograms, which you will meet later and have touching bars for continuous data.
条形图用于离散或分类数据。它们与直方图不同，直方图将在以后学习，用于连续数据且条形相连。
8. Pie Charts | 饼图
A pie chart displays data as slices of a circle. The whole circle represents the total frequency, and each slice (sector) shows a category’s proportion. The angle of each sector is calculated by:
饼图将数据展示为圆的扇形图块。整个圆代表总频数，每个扇形块显示一个类别的占比。每个扇形的角度计算公式为：
Sector angle = (Category frequency ÷ Total frequency) × 360°
扇形角度 = (类别频数 ÷ 总频数) × 360°
For example, if 15 out of 60 students prefer apples, the sector angle is (15 ÷ 60) × 360° = ¼ × 360° = 90°. Always use a protractor to draw accurate angles.
例如，如果 60 名学生中有 15 名喜欢苹果，扇形角度为 (15 ÷ 60) × 360° = ¼ × 360° = 90°。务必使用量角器来画出精确的角度。
Pie charts are excellent for showing proportions visually. The largest slice is the mode category – the one that pops out most.
饼图非常适合直观地显示比例。最大的扇形块就是众数类别——最引人注目的那一块。
9. Pictograms | 象形图
A pictogram uses pictures or symbols to represent data. Each symbol stands for a certain number of items. The key tells you what one symbol is worth.
象形图使用图片或符号来表示数据。每个符号代表一定数量的项目。图例告诉你一个符号代表多少。
For instance, one smiley face = 4 students. To show 10 students, draw 2.5 smiley faces. Pictograms make data easy to compare at a glance, but fractions of symbols require careful drawing.
例如，一个笑脸 = 4 名学生。要表示 10 名学生，就画 2.5 个笑脸。象形图让数据一目了然便于比较，但符号的分数部分需要细心绘制。
Remember: ‘Picture-gram’ – a graph made of pictures. Always check the key before reading the data!
记住：“Picture-gram”——用图画构成的图表。阅读数据前一定要先看图例！
10. Line Graphs | 折线图
A line graph shows how data changes over time. Points are plotted and then connected by straight lines. The horizontal axis usually represents time (days, months, years), while the vertical axis shows the quantity.
折线图显示数据随时间的变化。先描点，然后用直线连接各点。横轴通常表示时间（日、月、年），纵轴表示数量。
Look for trends: is the line going up (increasing), going down (decreasing), or staying flat (constant)? A steep line shows a rapid change, a gentle slope shows a slow change.
观察趋势：线条是上升（增加）、下降（减少）还是持平（不变）？陡峭的线表示变化快速，平缓的斜坡表示变化缓慢。
Line graphs help us make predictions. If the trend continues, we can estimate future values by extending the line (though this assumes the pattern won’t change).
折线图有助于预测。如果趋势继续，我们可以延长线条来估算未来的值（尽管这是假设模式不变）。
11. Comparing Data Sets | 比较数据集
To compare two sets of data, use mean, median, mode and range together. The mean or median tells you which set is generally larger; the range tells you which set is more consistent or more varied.
比较两组数据时，要综合使用均值、中位数、众数和极差。均值或中位数告诉你哪一组总体上更大；极差告诉你哪一组更稳定或更分散。
For example, Class A test scores: mean 72, range 30. Class B: mean 72, range 12. Both have the same average, but Class B’s smaller range means the scores are more consistent – less spread.
例如，A 班测验成绩：均值 72，极差 30。B 班：均值 72，极差 12。两者平均分相同，但 B 班较小的极差意味着成绩更稳定——分布更集中。
Always write a sentence comparing both central tendency and spread when asked. Use phrases like ‘on average, … is higher’ and ‘the range shows that … is more variable’.
当被要求比较时，一定要写一句话同时比较集中趋势和离散程度。使用诸如“平均而言……更高”以及“极差显示……变化更大”这样的表述。
12. Quick Revision Card: Top Terms at a Glance | 快速复习卡：核心术语一览
Keep this card handy for last-minute revision. Read the English term, recall its meaning, and check the Chinese equivalent. This builds a strong bilingual memory link.
随身携带这张复习卡用于考前冲刺。看到英文术语，回忆其意思，再核对中文对应词。这样能建立起强大的双语记忆联系。
| Term 术语 | Meaning 含义 | 中文 |
| Mean | Sum divided by count | 平均值 |
| Median | Middle value when ordered | 中位数 |
| Mode | Most frequent value | 众数 |
| Range | Largest minus smallest | 极差 |
| Frequency | How often something occurs | 频数 |
| Tally | Counting marks in groups of five | 记数符号 |
| Discrete data | Counted data (whole numbers) | 离散数据 |
| Continuous data | Measured data (any value) | 连续数据 |
| Population | Entire group being studied | 总体 |
| Sample | Smaller group chosen from population | 样本 |
Published by TutorHao | Statistics Revision Series | aleveler.com
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