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Ordinary Level Mathematics Revision Notes

Topic 1.7: Analysing Data

These notes explain Analysing Data in simple English so students can understand the topic clearly, not just memorise rules. The Ordinary Level version keeps the focus on the core ideas without unnecessary higher-only pressure.

Curriculum Irish Leaving Certificate
Subject Mathematics
Level Ordinary Level
Premium feature Teacher-style explanations and cleaner study flow
Focus
Understanding before memorising
Interactive
Study tools and guided structure
Question Style
Explained examples and exam practice
Format
Website reading and printable notes

Subtopics Covered

  • Measures of Central Tendency
  • Measures of Spread (Dispersion)
  • Higher Level: Inferences & Hypothesis
  • 📝 Exam Style Questions

What Makes This Version Better

  • Cleaner Ordinary Level focus with no unnecessary higher-only material
  • Simple teacher-style explanations before each method
  • Worked examples in clear stages
  • Cleaner page flow for student understanding
  • SEO-friendly website naming and branding
Disclaimer This publication is an independent educational resource developed by ExamsLogic and compiled by experienced educators. It is based on publicly available official curricula, including Cambridge, Pearson Edexcel, IB, and the Irish Leaving Certificate. This product is not endorsed by, affiliated with, or sponsored by any examination board or governing authority. All registered trademarks remain the property of their respective owners.
Start Reading Open Study Tools

Learning Objectives

What You Should Be Able To Do

    Interactive Study Tools

    These tools are here to help students slow down and think about the method before rushing to an answer.

    Tool 1

    Study Planner

    Use this to break a topic into small study sessions.

    Plan: A clear breakdown will appear here.
    Tool 2

    Method Reminder

    This quick guide reminds students what to do when they feel stuck.

    • Read the story: what is the question really asking?
    • Choose the method: identify the correct idea before calculating.
    • Show the reason: do not skip the logic.
    • Check the answer: make sure it fits the situation.

    1. Measures of Central Tendency

    Simple explanation: This section explains the main idea in simple English first, then builds toward the formal method used in exam questions.

    How do we find the "middle" of a dataset?

    • Mean: Add all values, divide by count. Sensitive to outliers.
    • Median: The middle value when ordered. Best for data with extreme outliers.
    • Mode: The most frequent value. Used for categorical data.

    2. Measures of Spread (Dispersion)

    Simple explanation: This section explains the main idea in simple English first, then builds toward the formal method used in exam questions.

    How "spread out" is our data?

    • Range: Max - Min. Very basic.
    • Interquartile Range (IQR): Q3 - Q1. Ignores the top and bottom 25% of data. Excellent for handling outliers.
    • Standard Deviation: Measures how much data deviates from the Mean.
    Examiner Tip
    💡 Examiner Tip: Always order your data numerically before finding the Median or Quartiles. Skipping this step is the #1 cause of lost marks!

    3. Higher Level: Inferences & Hypothesis

    Simple explanation: This section explains the main idea in simple English first, then builds toward the formal method used in exam questions.

    At HL, we move beyond describing data to making claims about the whole population using Margin of Error and Hypothesis Testing.

    Margin of Error ≈ 1 / √(sample size)

    📝 Exam Style Questions

    Simple explanation: This section explains the main idea in simple English first, then builds toward the formal method used in exam questions.

    Easy Q1: A dataset is {1, 2, 2, 4, 11}. Find the Mean and the Median.

    Medium Q2: Why is the Interquartile Range often better than the Range for comparing two datasets?

    A1: Mean = 20/5 = 4. Median = 2. (The outlier 11 pulls the mean up, but the median stays at 2).

    A2: The Range is heavily influenced by outliers (max/min). The IQR excludes the top and bottom 25%, making it more robust.