Data Presentation & Interpretation

This lesson covers the key methods for presenting and interpreting data at A-Level. You must be able to construct and interpret a wide range of diagrams and calculate summary statistics from both raw data and grouped frequency tables.

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Types of Data

Type	Description	Examples
Qualitative	Non-numerical, descriptive	Colour, gender, nationality
Quantitative discrete	Numerical, countable, specific values	Number of pets, shoe size
Quantitative continuous	Numerical, measurable, any value in a range	Height, weight, time

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Measures of Location (Averages)

Mean

The mean is the sum of all values divided by the number of values.

$\bar{x} = \frac{\sum x}{n} \quad \text{or for frequency data:} \quad \bar{x} = \frac{\sum fx}{\sum f}$xˉ=n∑x​or for frequency data:xˉ=∑f∑fx​

Median

The median is the middle value when data is arranged in order. For $n$n values, the median is the $\frac{n+1}{2}$2n+1​-th value.

Mode

The mode is the most frequently occurring value. Data can be bimodal (two modes) or have no mode.

Choosing the Appropriate Average