Year 8 - Maths
Changing a data point
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 see how certain statistical measures may change as a result of changes in the data.
Key Notes
- Changing the value of one data point can affect the mode.
- Changing the value of one data point can affect the median.
- Changing the value of one data point can affect the mean.
Vocabulary To Learn
- Bimodal: Sets of data which have two modes are known as bimodal data.
- Mean: The (arithmetic) mean for a set of numerical data is the sum of the values divided by the number of values.
- Median: The median is the central (middle) piece of data when a set of numerical data is in numerical order.
- Mode: The mode is the most frequent value in a dataset.
Common Mistakes To Avoid
- Averages (mean, median, mode) will always change if a data point needs to be added, removed, edited.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Changing the value of one data point can affect the mode. Changing the value of one data point can affect the median.
2. Use this key word in a maths sentence and explain it clearly. 'Bimodal'
Sets of data which have two modes are known as bimodal data. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Averages (mean, median, mode) will always change if a data point needs to be added, removed, edited. Correction: The mean, median, or mode will remain invariant if a data point is added with the same value as that average.
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
- Checking understanding of the mean Study Guide
- Comparing statistical representations Study Guide
- Comparing summaries of data Study Guide
- Correlation Study Guide
- Evaluating the range 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.