Lesson 4: Scatter Plots and Lines of Fit

Property

A scatter plot is a graph that displays data points to show the relationship between two variables. When the data points show a pattern that can be approximated by a straight line, this indicates a linear trend.

Examples

Property

Correlation describes the relationship between two variables in a scatter plot: Positive correlation occurs when both variables increase together (points trend upward from left to right), Negative correlation occurs when one variable increases while the other decreases (points trend downward from left to right), and No correlation occurs when there is no clear linear pattern between the variables (points appear randomly scattered).

Examples

Property

Correlation strength describes how closely data points cluster around a line of fit. Strong correlation means points lie close to the line with little scatter, while weak correlation means points are spread far from the line with much scatter.

Examples

Property

Positive slopes correspond to lines that increase from left to right.
Negative slopes correspond to lines that decrease from left to right.
The larger the absolute value of the slope, the steeper the graph.

Examples

• A line with slope $m = 2$ is steeper than a line with slope $m = \frac{1}{3}$ because $|2| > |\frac{1}{3}|$.

• A line with slope $m = -3$ is steeper than a line with slope $m = -1$ because $|-3| > |-1|$. Both lines slant downwards.