1. Do Now Create a scatterplot following these directions
Enter data in L1 and L2 (Stat-Edit)
Make sure your Plot 1 is ON and a scatterplot
To do this:
Go to 2nd – Y=
Turn plot 1 ON
Make sure 1st graph is highlighted
Hit Zoom 9 (Zoom - stat)

2. Lesson 3.1: Scatterplots and Describing a Relationship

3. Objectives
Distinguish between explanatory and response variables for quantitative data.
Make a scatterplot to display the relationship between two quantitative variables
Describe the direction, form, and strength of a relationship displayed in a scatterplot and identify unusual features.

4. A response variable measures an outcome of a study.
An explanatory variable may help predict or explain changes in a response variable.

5. Important Ideas Explanatory- always on x axis (horizontal)
Response – always on y axis (vertical)
D.U.F.S
Direction
Unusual Features or outliers
Form
Strength

6. Do now- Describe the following relationships using D.U.F.S

7. Correlation Coefficient
The correlation r is a measure of the strength and direction of a linear relationship between two quantitative variables.
• The correlation r is a value between -1 and 1 (-1 ≤ r ≤ 1).
• If the relationship is negative, then r < 0. If the relationship is positive, then r > 0.
• If r =1 or r = -1, then there is a perfect linear relationship. In other words, all of the points will be exactly on a line.
• If there is very little scatter from the linear form, then r is close to 1 or -1. The more scatter from the linear form, the closer r is to 0.

8. Equation

9. Equation

11. Guess the Correlation

12. To Calculate r…. Hit 2nd 0 (Brings us to CATALOG)
Scroll alllllll the way down to DiagnosticON (you only need to do this once, unless your calculator is reset or you use a different one)
Hit enter
And enter again. Should say “Done”
Enter data into L1 and L2 (Stat-Edit)
Then Stat-Calc –LinReg (a+bx) This is #8, not #4
r is your correlation coefficient!

13. Do now
Finish the front page of lesson 3.1 day 2 handout

14. Lesson 3.1 Day 2