Scatter plots, step by step
A scatter plot puts two measurements against each other and asks what the cloud of points is doing.
Is the pattern linear or nonlinear?
Is the pattern linear or nonlinear?
- A scatter plot puts two measurements against each other: Age (years) along the bottom, Price ($1000s) up the side, and one dot for each thing measured. There is no single dot to read off — every question here is about what the whole cloud is doing.
- Shape is about whether a straight line would follow the points, or whether they bend away from one. Sketch a line through the middle of the cloud with a finger and see.
- The points stay close to that straight line all the way along, so the pattern is LINEAR.
- So the answer is "linear". Say what that means for the two things rather than for the graph — and remember it is not a claim that one CAUSES the other. Two measurements can move together for a reason that is nothing to do with either of them.
How it works.
- 01
A scatter plot puts two measurements against each other: Age (years) along the bottom, Price ($1000s) up the side, and one dot for each thing measured. There is no single dot to read off — every question here is about what the whole cloud is doing.
- 02
Shape is about whether a straight line would follow the points, or whether they bend away from one. Sketch a line through the middle of the cloud with a finger and see.
- 03
The points stay close to that straight line all the way along, so the pattern is LINEAR.
- 04
So the answer is "linear". Say what that means for the two things rather than for the graph — and remember it is not a claim that one CAUSES the other. Two measurements can move together for a reason that is nothing to do with either of them.