📚 Year 8 WJEC Statistics: Key Terms Memory Guide | WJEC 八年级统计：词汇术语速记指南
Welcome to your quick-reference guide for the most important statistical terms you will encounter in Year 8 under the WJEC curriculum. Statistics can feel like learning a new language, but once you understand the building blocks — the key vocabulary — everything becomes much easier. This bilingual guide is designed to help you memorise definitions, understand context, and feel confident whether you are reading a question in English or discussing a concept in Chinese. Each section pairs a core term with a clear explanation in both languages, followed by examples and memory tips.
欢迎来到这本速记指南，这里整理了 WJEC 八年级统计课程中最重要的术语。统计学有时像在学一门新语言，但一旦你掌握了基础构件——也就是这些核心词汇——一切都会变得简单许多。这本双语指南旨在帮助你熟记定义、理解语境，无论你是用英文读题还是用中文讨论概念，都能自信应对。每个小节都将一个核心术语与清晰的双语解释配对，并提供例子和记忆技巧。
1. Data | 数据
Data is the plural of the word ‘datum’ and refers to a collection of facts, numbers, or observations that are recorded for analysis. In Year 8 statistics, data can come from surveys, experiments, or measurements. Without data, there is no statistics — it is the raw material of everything we do. Understanding what counts as data helps you decide how to collect and organise information before carrying out any calculations.
数据是单词 ‘datum’ 的复数形式，指为分析而记录的事实、数字或观察结果的集合。在八年级统计中，数据可以来自调查、实验或测量。没有数据就没有统计学——它是我们一切工作的原材料。理解什么算作数据，有助于你在进行任何计算之前决定如何收集和整理信息。
2. Qualitative and Quantitative Data | 定性数据与定量数据
Data can be split into two broad types. Qualitative data describes qualities or characteristics that cannot be measured with numbers, such as eye colour or favourite food. Quantitative data is numerical and tells you how many or how much, like height in centimetres or the number of pets someone owns. A quick memory trick: ‘qualitative’ relates to ‘quality’ (descriptive), and ‘quantitative’ relates to ‘quantity’ (numbers).
数据可以分为两大类。定性数据描述的是无法用数字衡量的性质或特征，比如眼睛颜色或最喜欢的食物。定量数据是数字形式的，告诉你数量是多少，比如身高（厘米）或某人所养宠物的数量。一个快速记忆技巧：’定性’与’性质’相关（描述性的），而’定量’与’数量’相关（数字）。
3. Discrete and Continuous Data | 离散数据与连续数据
Quantitative data comes in two further flavours. Discrete data can only take specific, separate values — you count it, like the number of students in a class (29, 30, 31, never 29.5). Continuous data can take any value within a range — you measure it, like time taken to run 100m (12.3 seconds, 12.33 seconds, and so on). This distinction matters because it affects the types of charts and statistics you should use.
定量数据又分为两种类型。离散数据只能取特定的、分开的值——你是数出来的，比如班级里的学生人数（29、30、31，绝不会是29.5）。连续数据可以取某个范围内的任何值——你是测量出来的，比如跑100米所用的时间（12.3秒、12.33秒等等）。这个区别很重要，因为它会影响你应使用的图表类型和统计量。
4. Mean | 平均数
The mean is the most common measure of average. To find it, you add up all the values in a data set and then divide by the number of values. The formula looks like this:
平均数是最常见的平均值度量。计算方法是：把数据集里所有数值加起来，然后除以数值的个数。公式如下：
Mean = (Sum of all values) ÷ (Number of values)
For example, the mean of 4, 8, and 12 is (4 + 8 + 12) ÷ 3 = 8. The mean is useful, but it can be pulled up or down by extreme values, which is why you need to know other averages too.
例如，4、8、12 的平均数是 (4 + 8 + 12) ÷ 3 = 8。平均数很有用，但它可能被极端值拉高或拉低，因此你还需要了解其他的平均值。
5. Median | 中位数
The median is the middle value when all the numbers are arranged in order from smallest to largest. If there is an odd number of values, the median is simply the one exactly in the middle. If there is an even number of values, you find the mean of the two middle numbers. The median is often used when data contains outliers because it is not distorted by them.
中位数是将所有数字从小到大排列后处于中间位置的值。如果数值个数是奇数，中位数就是正中间的那个数；如果数值个数是偶数，则取中间两个数的平均数。中位数常用于包含异常值的数据，因为它不会被异常值扭曲。
6. Mode | 众数
The 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 if all values appear equally often. The mode is the only average that can be used with qualitative data — for example, ‘blue’ is the mode if most people in a survey chose blue as their favourite colour.
众数是数据集中出现频率最高的值。一组数据可以有一个众数、多个众数（双众数或多众数），或者如果所有值出现次数相同则没有众数。众数是唯一可用于定性数据的平均值——例如，如果一项调查中大多数人选择蓝色作为最喜欢的颜色，那么’蓝色’就是众数。
7. Range | 极差
The range is a simple measure of spread. You calculate it by subtracting the smallest value from the largest value in the data set. A larger range tells you the data is more spread out. While it is quick to calculate, the range only uses two numbers and does not tell you about the distribution of values in between.
极差是一种简单的离散程度度量。计算方法是用数据集中的最大值减去最小值。极差越大，说明数据越分散。虽然极差计算起来很快，但它只用了两个数字，无法告诉你中间数值的分布情况。
8. Frequency | 频数
Frequency simply means how often something occurs. When you count the number of times each value appears in a data set, you are finding its frequency. A frequency table organises data by listing each value or category alongside its frequency, making patterns easier to spot.
频数就是某件事发生的次数。当你清点数据集中每个值出现的次数时，你就是在找它的频数。频数表通过列出每个值或类别及其对应的频数来整理数据，让规律更容易被发现。
9. Data Collection and Primary / Secondary Data | 数据收集与一手/二手数据
Data can be collected in different ways. Primary data is information you gather yourself for a specific purpose, such as conducting a questionnaire or running an experiment. Secondary data is information that someone else has already collected, like data found in books, websites, or government reports. Knowing the difference helps you evaluate how reliable and relevant your data might be.
数据可以通过不同方式收集。一手数据是你自己为特定目的而收集的信息，比如进行问卷调查或做实验。二手数据是别人已经收集好的信息，比如在书籍、网站或政府报告中找到的数据。了解它们的区别有助于你评估数据的可靠性和相关性。
10. Bar Chart and Pictogram | 条形图与象形图
A bar chart uses rectangular bars to represent frequencies or values for different categories, where the length of each bar is proportional to the number it represents. Bar charts are great for comparing discrete categories. A pictogram uses small pictures or symbols to show frequencies, with each picture representing a fixed number of items. Both charts require a clear title and labelled axes or keys.
条形图用矩形条来表示不同类别的频数或数值，每个条的长度与其所代表的数值成比例。条形图非常适合比较离散类别。象形图用小图片或符号来表示频数，每个图片代表固定数量的物品。这两种图表都需要清晰的标题以及标注清楚的坐标轴或图例。
11. Pie Chart | 饼图
A pie chart is a circular chart divided into sectors, where each sector’s angle represents the proportion of a category in the whole data set. The entire circle (360°) represents the total. To find the angle for a section, you multiply the fraction of the total by 360°. Pie charts are useful for showing how a whole is divided, but they work best with a small number of categories.
饼图是一种划分为扇形的圆形图表，每个扇形的角度代表该类别在整个数据集中所占的比例。整个圆（360°）代表总数。要计算某个扇形的角度，你需要用该部分占总量的分数乘以360°。饼图适合展示整体的划分情况，但在类别数量较少时效果最佳。
12. Line Graph | 折线图
A line graph plots data points on a coordinate grid and connects them with straight lines. The horizontal axis (x-axis) usually represents time or another continuous variable, while the vertical axis (y-axis) shows the measured values. Line graphs are particularly good for showing trends and changes over time, such as temperature changes during a week or a company’s monthly sales.
折线图在坐标网格上标出数据点，并用直线将它们连接起来。横轴（x 轴）通常表示时间或其他连续变量，而纵轴（y 轴）表示测量值。折线图特别适合显示随时间变化的趋势，比如一周内温度的变化或一家公司的月销售额。
Published by TutorHao | Statistics Revision Series | aleveler.com
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