Microsoft Office Tutorials and References

In Depth Information

(actually it is 82.48), the result above for predicting the

number of eggs produced from a ﬁsh weighing 3,500 g.

For a more detailed discussion of regression, see Black (Black
2010
) and Gould

and Gould (
2002
).

6.6 Adding the Regression Equation to the Chart

Objective: To Add the Regression Equation to the Chart

If you want to include the regression equation within the chart next to the

regression line, you can do that, but a word of caution ﬁrst.

Throughout this topic, we are using the regression equation for one predictor

and one criterion to be the following:

Y
¼
a
þ
bX

ð
6
:
3
Þ

where a = y-intercept and b = slope of the line

See, for example, the regression equation in
Sect. 6.5.3
where the y-intercept

was a = 24.73 and the slope of the line was b = +0.0165 to generate the

following regression equation:

Y
¼
24
:
73
þ
0
:
0165 X

However, Excel 2010 uses a slightly different regression equation (which is

logically identical to the one used in this topic) when you add a regression

equation to a chart:

Y
¼
bX
þ
a

ð
6
:
4
Þ

where a = y-intercept and b = slope of the line

Note that this equation is identical to the one we are using in this topic with the

terms arranged in a different sequence.

For the example we used in
Sect. 6.5.3
, Excel 2010 would write the regression

equation on the chart as:

Y
¼
0
:
0165 X
þ
24
:
73

This is the format that will result when you add the regression equation to the

chart using Excel 2010 using the following steps:

Open the ﬁle: eggs36 (that you saved in
Sect. 6.5.2)

Click just inside the outer border of the chart in the top right corner to add the

‘‘gray border’’ around the chart in order to ‘‘select the chart’’ for

changes you are about to make

Right-click on any of the data-points in the chart

Highlight: Add Trendline

The ‘‘Linear button’’ near the top of the dialog box will be selected (on its left)

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