High-Frequency Topics and Common Error Analysis in Cambridge IGCSE Statistics | IGCSE Cambridge 统计高频考点与易错题分析

📚 High-Frequency Topics and Common Error Analysis in Cambridge IGCSE Statistics | IGCSE Cambridge 统计高频考点与易错题分析

Cambridge IGCSE Statistics rewards students who can describe data clearly, calculate probabilities accurately and interpret results in context. This revision article summarises the most frequently examined topics and highlights the mistakes that repeatedly cost marks. Use the paired English-Chinese notes to revise actively: cover one language, test yourself, then check.

剑桥 IGCSE 统计考查学生清晰描述数据、准确计算概率以及在情境中解释结果的能力。本文总结最高频的考点，并突出反复导致失分的错误。使用中英对照笔记进行主动复习：遮住一种语言，自测后再核对。

1. Types of Data and Sampling Methods | 数据类型与抽样方法

Data can be qualitative (non-numerical, such as eye colour) or quantitative (numerical). Quantitative data is further split into discrete data, which can only take exact values, and continuous data, which can take any value in a range.

数据可以是定性数据（非数值，如眼睛颜色）或定量数据（数值）。定量数据又分为离散数据（只能取精确值）和连续数据（在一个范围内可取任意值）。

A common trap is treating shoe size as continuous because it has halves. Shoe size is discrete because only certain sizes exist; height is continuous because it can be 162.3 cm, 162.35 cm and so on.

常见陷阱是认为鞋码有半码就是连续数据。鞋码是离散数据，因为只有某些尺码存在；身高是连续数据，因为它可以是 162.3 cm、162.35 cm 等等。

For sampling, random sampling gives every member an equal chance. Stratified sampling divides the population into groups and takes a sample proportional to each group’s size: n_stratum = (group size ÷ population size) × total sample size.

在抽样中，随机抽样使每个成员被抽中的机会相等。分层抽样将总体分成层，并按每层大小的比例抽样：层样本量 = (层大小 ÷ 总体大小) × 总样本量。

If a stratified sample of 60 is taken from 300 boys and 200 girls, choose boys: (300 ÷ 500) × 60 = 36, girls: (200 ÷ 500) × 60 = 24. Many errors come from forgetting to multiply after finding the fraction.

如果从 300 名男生和 200 名女生中抽取 60 人的分层样本，男生应抽：(300 ÷ 500) × 60 = 36，女生：(200 ÷ 500) × 60 = 24。很多错误来自算出比例后忘记乘以总样本量。

2. Charts for Discrete and Continuous Data | 离散与连续数据的图表

Bar charts are used for discrete or categorical data, and the bars usually have gaps between them. Pie charts show proportions, with each angle calculated as (frequency ÷ total frequency) × 360°.

条形图用于离散或分类数据，条形之间通常有空

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