Summary Statistics Notes
Simple and Easy-to-Read Guide
What Are Summary Statistics?
Summary statistics are numbers that describe and summarise the main features of a
dataset. They help us understand large amounts of data quickly and easily.
Key Types of Summary Statistics
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Measures of Central Tendency
Mean (Average): Add all values together and divide by the number of values.
Median: The middle value when all numbers are put in order.
Mode: The value that appears most often in a dataset.
Measures of Spread (Variation)
Range: The difference between the highest and lowest values.
Variance: The average of the squared differences from the Mean.
Standard Deviation: Shows how much the values vary from the Mean.
Other Useful Summary Statistics
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Minimum: The smallest value in the dataset.
Maximum: The largest value in the dataset.
Quartiles: Values that split the data into four equal parts. The second quartile
is the Median.
Percentiles: Show the value below which a given percentage of data falls.
Why Use Summary Statistics?
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To get a quick overview of the data
To identify patterns and outliers
To compare different datasets
Key Points to Remember
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Summary statistics make data easier to understand.
Mean, Median, and Mode help you understand the centre of the data.
Range, Variance, and Standard Deviation show how spread out the data is.
Minimum and Maximum provide the boundaries of the data values.
Example
Given the dataset: 2, 4, 4, 5, 7
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Mean: (2+4+4+5+7) / 5 = 4.4
Median: 4 (middle value)
Mode: 4 (appears most often)
Range: 7 - 2 = 5
Minimum: 2
Maximum: 7
Conclusion
Summary statistics are basic tools for understanding data. They help to quickly
describe and compare datasets without looking at every single value.