Microsoft Office Tutorials and References

In Depth Information

We can now write the multiple regression equation for these data:

Y
¼
1
:
5363
þ
0
:
0006 X
1
þ
0
:
0003 X
2
þ
0
:
0021 X
3

7.3 Using the Regression Equation to Predict FROSH GPA

Objective:

To ﬁnd the predicted FROSH GPA using an SAT Reading Score of

600, an SAT Writing Score of 500, and an SAT Math Score of 550

Plugging these three numbers into our regression equation gives us:

Y
¼
1
:
5363
þ
0
:
0006 60
ðÞþ
0
:
0003 50
ðÞþ
0
:
0021 55
ðÞ

Y
¼
1
:
5363
þ
0
:
36
þ
0
:
15
þ
1
:
155

Y
¼
3
:
20

ð

since GPA scores are typically measured in two decimals

Þ

If you want to learn more about the theory behind multiple regression, see

Keller (
2009
) and Gould and Gould (
2002
).

7.4 Using Excel to Create a Correlation Matrix in Multiple

Regression

The ﬁnal step in multiple regression is to ﬁnd the correlation between all of the

variables that appear in the regression equation.

In our example, this means that we need to ﬁnd the correlation between each of

the six pairs of variables:

To do this, we need to use Excel to create a ‘‘correlation matrix.’’ This matrix

summarizes the correlations between all of the variables in the problem.

Objective:

To use Excel to create a correlation matrix between the four variables

in this example

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