📚 Year 10 WJEC Statistics: Exam Techniques and Marking Criteria | Year 10 WJEC 统计：答题技巧与评分标准
Mastering Year 10 WJEC Statistics requires more than just knowing formulas and definitions. Examiners award marks for method, accuracy, and clear communication. This article breaks down the key exam techniques and explains how marks are allocated, helping you avoid common pitfalls and score more highly.
掌握 Year 10 WJEC 统计不仅仅需要记住公式和定义。考官会给方法、准确性和清晰的表达打分。本文解析关键答题技巧并说明评分规则，帮你避开常见陷阱、拿到更高分数。
1. Understand the Command Words | 理解指令词
WJEC exam questions use precise command words such as ‘Calculate’, ‘Describe’, ‘Compare’, and ‘Explain’. Each requires a specific type of response. For ‘Calculate’, you must show all steps and arrive at a numerical answer. For ‘Describe’, you should state what you see in data or a graph, quoting figures where relevant.
WJEC 考题会使用精确的指令词，如“计算”、“描述”、“比较”和“解释”。每个词都对应一种特定的回答方式。“计算”要求展示所有步骤并得出数字答案。“描述”则需要陈述数据或图表中看到的现象，必要时引用数字。
‘Compare’ means you must discuss similarities and differences, often using comparative words like ‘higher’, ‘lower’, or ‘more spread out’. ‘Explain’ or ‘Give a reason’ asks you to link a statistical concept to the context, not just state a rule.
“比较”意味着你必须讨论相似之处和不同之处，通常使用“更高”、“更低”或“更分散”等比较词。“解释”或“给出理由”要求你将统计概念与情境联系起来，而不仅仅是陈述规则。
2. Show Your Working Out | 展示解题过程
Examiners award method marks (M marks) for clear, logical steps. Even if your final answer is wrong, you can still earn most of the marks. Always write down the formula you intend to use, substitute the numbers, and then calculate.
考官会为清晰、有逻辑的步骤给方法分（M 分）。即使最终答案错了，你仍能拿到大部分分数。务必写出你打算使用的公式，代入数字，然后再计算。
For example, when finding the mean from a frequency table, do not just write the answer. Write: ‘Mean = Σfx ÷ Σf’. Show the sum of the frequency column and the sum of the fx column. This proves you understand the process.
例如，在利用频数表求均值时，不要只写答案。写出：“均值 = Σfx ÷ Σf”。展示频数列之和与 fx 列之和。这能证明你理解过程。
Similarly, for the median from a list, first order the data. If n = 15, the median is the 8th value. Write ‘(15+1)/2 = 8th value’ to secure the method mark.
同样，从列表中找中位数时，先排序数据。如果 n = 15，中位数就是第8个值。写下“(15+1)/2 = 第8个值”以确保得到方法分。
3. Accuracy and Rounding | 精确度与舍入
WJEC mark schemes often state ‘Accept answers rounding to 3 significant figures unless specified otherwise’. Avoid rounding intermediate values; use the full calculator display or at least 4 significant figures for further calculations. Final answers should be rounded sensibly to 3 s.f. or 2 decimal places for money.
WJEC 评分方案常写明“除非另有规定，答案四舍五入至3位有效数字即可”。避免对中间值进行舍入；后续计算应使用完整的计算器显示值或至少4位有效数字。最终答案应合理舍入至3位有效数字或金额保留2位小数。
Common error: writing a probability as ⅓ but then giving 0.3 in decimal form. Always check if the question asks for a fraction, decimal, or percentage. If no format is given, a simplified fraction or a decimal to 3 s.f. is safe.
常见错误：把概率写成 ⅓ 但小数却写成 0.3。务必检查题目要求的是分数、小数还是百分比。若没指定格式，用简化分数或3位有效数字的小数最为稳妥。
In drawing graphs or measuring angles for pie charts, use a sharp pencil and measure to the nearest degree. A tolerance of ±2° is usually accepted, but always aim for accuracy.
画图或测量饼图角度时，要用尖铅笔，测量精确到最近的角度。通常允许 ±2° 的误差，但始终要力求准确。
4. Interpreting Graphs and Charts | 解读图表
When reading a histogram, remember that frequency = frequency density × class width. Many candidates lose marks by reading the frequency density as the frequency. Always check the vertical axis label.
解读直方图时，记住频率 = 频率密度 × 组距。许多考生因把频率密度当成频率而失分。始终检查纵轴标签。
For comparative cumulative frequency curves or box plots, you may be asked to compare medians and interquartile ranges. Use exact figures: ‘The median for group A is 62 marks, which is 8 marks higher than group B.’ Simply writing ‘Group A did better’ is not enough.
对于比较型累积频率曲线或箱线图，你可能需要比较中位数和四分位距。要使用确切数字：“A组的中位数是62分，比B组高8分。”只写“A组表现更好”是不够的。
Pie charts: always check if the total frequency is given. To find an angle, use (category frequency ÷ total) × 360°. Label each sector clearly or provide a key.
饼图：始终检查是否给出总频数。要计算角度，使用（类别频数 ÷ 总频数）× 360°。清晰标注各扇区或提供图例。
5. Probability and Tree Diagrams | 概率与树状图
All probabilities must be between 0 and 1. When using tree diagrams, write the probability on each branch as a fraction or decimal. For independent events, multiply along the branches; for mutually exclusive outcomes, add the relevant probabilities.
所有概率值必须在0到1之间。使用树状图时，把每条分支的概率写成小数或分数。独立事件沿分支相乘；互斥结果则将相关概率相加。
Always check that the probabilities on branches from a single point sum to 1. If the question involves conditional probabilities, the second set of branches will change. Clearly label the events and show the final answer in its simplest form.
确保单点出发的各分支概率之和为1。如果问题涉及条件概率，第二组分支的概率值会改变。明确标注事件，并把最终答案写成最简形式。
A common pitfall is mixing up ‘and’ (×) with ‘or’ (+). Underline key words in the question to avoid this.
常见的陷阱是混淆“且”（×）和“或”（+）。在题目中勾画关键词以避免此类错误。
6. Averages and Measures of Spread | 平均数与离散度量
Know your formulae: Mean = Σx ÷ n. For grouped data, use midpoints. Mode is the most frequent value; for grouped data, the modal class interval. Median position = (n+1)/2 for raw data.
熟记公式：均值 = Σx ÷ n。对于分组数据，使用组中值。众数是最常出现的值；对于分组数据，则是众数组距。中位数的位置：未分组数据用 (n+1)/2。
To find quartiles, find the median of the lower half for Q₁, and the median of the upper half for Q₃. Interquartile range (IQR) = Q₃ − Q₁. Always state the IQR, as it measures spread, not just the range.
求四分位数时，找出下半部分的中位数作为 Q₁，找出上半部分的中位数作为 Q₃。四分位距（IQR）= Q₃ − Q₁。务必给出 IQR，因为它度量的是离散度，而不仅是全距。
When comparing two data sets, always quote a measure of central
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