1
Statistics:
An Introduction
Fifth Edition
584
Section 16:
Regression
A.
Introduction
Regression
– Use scores from one variable to
predict scores on a second variable.
Examples
:
Predict Income from education
Predict college grades from ACT test scores
Predict college grades from high school grades
Predict reading test scores from math test scores
585
Section 16:
Regression
Example Data from Section 14
Student
Math
Reading
1
50
45
2
45
50
3
60
55
4
70
60
5
60
40
6
30
35
7
40
40
8
50
55
9
40
35
10
40
60

This
** preview**
has intentionally

**sections.**

*blurred***to view the full version.**

*Sign up*
2
586
Section 16:
Regression
Show data as a Scatter Diagram
Students with high math scores tend to have high
reading scores.
But, relationship not perfect.
587
Section 16:
Regression
Refer to Data
- Options
Could predict scores using mean scores on reading
for particular scores on math.
What is average Reading score for people with
Math score of 40?
(40+35+60)/3=45
What is average Math score for people with reading
score of 50?
(45+55)/2=50
Could use these averages as predicted values.
Problem:
Each prediction based on small number
of scores.
588
Section 16:
Regression
Could draw a line and use the line to make
predictions:
See Scatterdiagram.
Draw a line.
What is predicted value for a math score of 40?
Of
50?
Or 55?
How would we have obtained predicted score for a
math score of 55 taking averages?
Problem:
Drawing line by hand subject to error.
Depends on person drawing the line.