Data with two variables
Displaying data with two variables
When investigating the relationship between two quantitative variables we draw a scatterplot.
- When drawing a scatterplot the convention for plotting graphs applies.
- The independent variable is placed on the horizontal axis.
- The dependent variable is placed on the vertical axis.
- When looking at the graph, you need to consider the:
- Form — does it resemble a straight line or another type of function?
- Direction — if it is resembles a straight line, what direction is it going (positive — up, or negative — down)
- Scatter — are the points scattered close to a line or do they have a large scatter?
- If the relationship appears to be a straight line you can draw a line of best fit.