Year 8 - Maths
Evaluating the range
Numerical summaries of data
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit pupils explore the concept of measures of central tendancy, developing understanding of different types of average and their relative benefits and drawbacks. We then investigate other summaries of data such as the range and data comparison techniques.
Lesson Summary
You will learn to evaluate the range as a measure of spread, including a consideration of outliers.
Key Notes
- The range can be affected by outliers in the data.
- Removing these outliers will change the value of the range.
- Outliers must be carefully considered and only removed if they were recorded in error.
Vocabulary To Learn
- Outlier: A data point that is extremely large or small compared to the rest of the dataset.
- Range: A measure of spread. It is found by finding the difference between the highest and lowest values.
- Spread/dispersion: Describes how far apart pieces of data in a dataset are.
Common Mistakes To Avoid
- "Adding or removing a data point from a dataset will always change the value of the range"
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
The range can be affected by outliers in the data. Removing these outliers will change the value of the range.
2. Use this key word in a maths sentence and explain it clearly. 'Outlier'
A data point that is extremely large or small compared to the rest of the dataset. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: "Adding or removing a data point from a dataset will always change the value of the range". Correction: The range only changes if: the data point added becomes a new max or min value, or the data point removed is the current max or min value.
More Lessons In This Unit
- Analysing different statistical representations Study Guide
- Calculating the mean Study Guide
- Calculating the median Study Guide
- Calculating the mode Study Guide
- Changing a data point Study Guide
- Checking understanding of the mean Study Guide
- Comparing statistical representations Study Guide
- Comparing summaries of data Study Guide
- Correlation Study Guide
- Problem solving with numerical summaries of data Study Guide
- Statistical problems - data collection Study Guide
- Statistical problems - data presentations Study Guide
- Statistical problems - drawing conclusions Study Guide
- Statistical problems - statistical summaries Study Guide
- Summarising data Study Guide
- Understanding and calculating the range Study Guide
- Understanding the median Study Guide
- Understanding the mode Study Guide
Browse all guides in the Year 8 Maths guide library.