1. Investigating Scatter Plots Section 2.5

2. Investigating Scatter Plots

3. Investigating Scatter Plots • Scatter plots are similar to line graphs in that each graph uses the horizontal ( x ) axis and vertical ( y ) axis to plot data points. • Scatter plots are most often used to show correlations or relationships among data.

4. Investigating Scatter Plots • Positive correlations occur when two variables or values move in the same direction. • As the number of hours that you study increases your overall class grade increases

5. Investigating Scatter Plots – Positive Correlation

6. Investigating Scatter Plots • Negative Correlations occur when variables move in opposite directions • As the number of days per month that you exercise increases your actual weight decreases

7. Investigating Scatter Plots – Negative Correlation

8. Investigating Scatter Plots • No correlation exists if there is no noticeable pattern in the data • There is no relationship between the number of shirts someone owns and their annual salary

9. Investigating Scatter Plots – No Correlation

10. Line of Best Fit • A line of best fit is a line that best represents the data on a scatter plot. • A line of best fit may also be called a trend line since it shows us the trend of the data • The line may pass through some of the points, none of the points, or all of the points. • The purpose of the line of best fit is to show the overall trend or pattern in the data and to allow the reader to make predictions about future trends in the data.

11. Use the data to create a scatter plot

12. Scatter Plot of the Data

13. Things to remember • A scatter plot with a positive correlation has X and Y values that rise together. • A scatter plot with a negative correlation has X values that rise as Y values decrease • A scatter plot with no correlation has no visible relationship • The line of best fit is the line that best shows the trend of the data