1. 2.5 Correlation and Best-Fitting Lines

2. In this lesson you will:
Use a scatter plot to identify the correlation shown by a set of data.
Approximate the best-fitting line for a set of data.

3. Scatter Plot
A scatter plot is a graph used to help determine whether there is a relationship between paired data.
Sometimes scatter plots follow patterns that are approximately linear.

4. Scatter Plot
In the scatter plot shown, y tends to increase as x increases.
Positive Correlation
We say the paired data has a positive correlation.

5. Scatter Plot
In the scatter plot shown, y tends to decrease as x increases.
Negative Correlation
We say the paired data has a negative correlation.

6. Scatter Plot No Correlation No Linear Pattern??
We say the paired data has a Relatively no correlation.

7. Approximating Best-Fitting Lines for a Scatter Plot
Sketch a line that appears to the pattern of the line.
(9,6)
There should be as many points above the line are there are below the line.
(-1,-4)
Pick two points on the line, and estimate the coordinates of each. These two points do not have to be original data points.
Use the point-slope formula to find the equation of the line.
y = x-3
This equation models the data

10. Homework 9-21 odd, all