1. Applying linear and median regression
Lab 8
Applying linear and median regression

2. Graphing calculators can be used to calculate and plot a line of best fit using linear regression
Use the data on p. 323
Calculate and plot linear regression from the table
Practice p. 324 a

3. Finding the line of best fit
Lesson 45
Finding the line of best fit

4. regression
Regression is the process of identifying a relationship between variables.
A measure of the strength and direction of the relationship between 2 variables or data sets is called correlation

5. Linear correlation
When the points tend to gather about a line, there is a linear relationship, or linear correlation.
A scatter plot of the points will indicate whether there is a positive correlation (points rise from left to right) or a negative correlation (points fall from left to right)
When the points are widely scattered, there will be little or no correlation

6. Line of best fit
A line that best fits the points in a scatter plot is a line of best fit ( or regression line)
A line of best fit will have about the same number of points above and below it.
It may or may not go through one or more of the points on the graph

7. Describing correlation and estimating a line of best fit
Create a scatter plot of the following data:
# of people in house
Aver. mail per day
Plot points (people,mail)
Since the points rise from left to right , there is a positive correlation.
Sketch the line of best fit
Use 2 points to find the slope and point-slope form to write an equation of the line

8. Correlation coefficient
The strength and direction of a linear correlation is measured by the correlation coefficient, r.
Values of r can range from -1 to 1, where negative values indicate negative correlation and positive values indicate positive correlation.
The further r is from 0, the closer the points are to a straight line
When there is no correlation, r = 0

9. Estimating the r value
Once you create a scatter plot, you can estimate the r value by remembering that the closer the points are to a straight line the closer the correlation is to -1 or 1

10. Using the graphing calculator
Enter data into L1 and L2
Be sure you go to CATALOG and scroll down to DIAGNOSTICSON and press ENTER twice
Follow directions as in lab 8
The r is the correlation.

11. Collecting and analyzing data
Step 1: 1 student bounces a tennis ball and one student times how long it takes for the ball to stop bouncing, while the other students count the number of times the ball bounces during that time. Do this 10 times.
Step 2: record the number of seconds that ball bounces and number of bounces.
Step 3: plot points, sketch line of best fit, find equation of line, and estimate the correlation coefficient