Statistics

An overview of the Statistics topic, covering data classification, interpretation, averages, charts, scatter diagrams, cumulative frequency, and histograms.

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The Detective's Toolkit

You know how to calculate probabilities. Now let us collect, display, and summarise real-world data.

Statistics isn't about boring numbers; it's about discovering what the world is actually doing. You gather data, organize it into tables and charts, then calculate summaries like the mean and median that capture the whole story in a few words.

Key idea

You'll move from staring at a messy pile of information to making powerful, evidence-based conclusions.

Memory trick

Think of Statistics as a S.T.A.R. — you Sort the data, build a Table or chart, find the Average, and then Report what you see.

What You Will Learn

You will follow the S.T.A.R. route: sort the data into tables, build the right chart for it, calculate the averages, and read the story back out.

Steps

1
Mean, median, mode and range, and finding them from a frequency table.
2
Grouped data: estimating the mean when you only have class intervals.
3
Displaying data: tally charts, pictograms, bar charts, pie charts and stem-and-leaf.
4
Scatter diagrams and correlation.
5
Histograms, for equal and then unequal class intervals.
6
Cumulative frequency: building the table, drawing the curve, and reading off the median and quartiles.

Formula

The one that catches people out: on a histogram the height is frequency density, not frequency.

frequency density = \frac{frequency}{class width}

So it is the area of the bar that tells you how many.

Practise statistics now

Interactive visual aids, then real past-paper questions marked on your working like the exam. Free to start.

Practise free on Lemmara

Lemmara is an independent study tool, not affiliated with or endorsed by Cambridge International Education or Pearson Edexcel. The lessons and worked examples are Lemmara’s own.