Scatter graphs
A scatter graph plots two variables to reveal how they are linked.
So far your charts have shown one kind of data. A scatter graph is different — it plots two variables together to reveal whether they are connected.
Each item gives one point: one variable along the horizontal axis, the other up the vertical axis. You do not join the points — the picture they make as a cloud is what matters.
In the graph each point is one student — their revision hours and their test score. The points are not joined; instead you look at the overall pattern they form.
To draw a scatter graph, label both axes with sensible, even scales, then plot each pair of values as a single point. The shape of the cloud is the whole point — and reading that shape is the next idea, correlation.
- A scatter graph plots two variables, one on each axis.
- Each item of data becomes a single point.
- The points are not joined up.
- The overall pattern of the cloud is what you read.