1. 2. Find the equation of line of regression
Objectives:
1: Graph Scatter Plots
2. Find the equation of line of regression
3. Find the correlation coefficient
Standard DA 3.6, 3.8, 3.9 Relationship between two variables Lesson 10.1

2. Key words 1. Scatter Plot 2. Regression 3. Line of Regression
4. Sample Correlation Coefficient
5. Population Correlation Coefficient

3. Scatter Plot
A scatter plot is a graph of the ordered pairs (x, y) of numbers consisting of the independent variable x and the dependent variable y.
Example: x 12 17 40 47 55 62 y 59 44 31 27 20 10

4. Regression
Regression is a statistical method to describe the nature of the relationship between variables, that is, positive or negative, linear or non linear.
Example: See the graph in previous example and find the line of regression.

5. correlation coefficient
It tells the strength and direction of a linear relationship between two variables.
Formula:

6. Graph scatter plot, line of regression, and find the correlation coefficient.
Page 549: problem 14: x 72 69 58 47 84 62 57 45 y 42 19 26 51 15 30

7. What we know from correlation coefficient
0 – very weak
0.2 – weak
0.5 – strong
0.8 – very strong
If coefficient is positive then relationship is positive, if it is negative then relationship is negative.
Special case: if coefficient is zero there is no relationship.
What we know from correlation coefficient

8. Practice/homework
Textbook:
Page 549: 18
Page 550: 20, 22, 23, 24