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Appendix I
How to Graph the Data in Excel
A graph provides a nice visual way to map two numerical variables. A line chart distributes data
points evenly along the horizontal axis (x-axis), but only shows a general trend in the data.
XY scatter charts are similar to line charts but show correct spacing between points. The individual
points that appear on the chart can be interpreted to express a trend, or, that there is a lack of a trend.
Additionally, a statistical equation can be produced via use of the software to describe the relationship
between the two variables and a line can be produced to show this relationship.
Consider the following data showing heart rate for two subjects (Harry and Sally), measured at
various times after the start of an exercise routine. Note that a few of the times recorded (minutes after
starting the exercise) are slightly different for Harry versus Sally.
Sally
Exercise Time
minutes
Heart Rate
bpm
0
10
18
24
32
38
40
50
58
60
64
68
88
114
122
134
145
152
Exercise Time
minutes
Harry
0
10
20
24
36
40
44
50
60
Heart Rate
bpm
64
68
76
90
132
152
158
160
168
These data will be represented differently on a line chart (with even spacing) than a scatter chart
(appropriate spacing).
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HOW TO CREATE A SCATTER CHART:
A) Arrange the data in columns. For this example, consider the following data:
Sally
Exercise Time
Heart Rate
minutes
0
10
18
24
32
38
40
50
58
bpm
60
64
68
88
114
122
134
145
152
Note that the data in the column labeled "Exercise Time - minutes" are in descending order.
These data will be graphed as the x-axis (horizontal axis).
B. Select the data in the rows or columns to include in the chart. To do this, click on the first
cell you want included in your chart and while holding down the mouse button, drag your
mouse to highlight the rest of the data you want on your chart.
In this example, click on the “0” and while holding down the mouse button, highlight the rest
of the two columns of data.
C. Click on "Insert" in the upper File menu and select "Scatter" from the "Chart" options.
Choose and click on the chart subtype you want from the pictures (for example, do you want
the individual points connected by a line or not).
D. You can move the chart to any location in your worksheet by clicking on it and dragging it
when you see the four-way arrow.
E. Adjust the size of the chart by moving each side, and the top and bottom in or out with your
mouse.
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160
140
120
100
80
Series1
60
40
20
0
0
20
40
60
80
F. Make the graph easier to read by adding axis labels. Under "Chart Options", click on the
box that says "Chart Title." You can give this graph a title if you'd wish. Then click on the box
that says "Chart Title" and choose the "Horizontal (Category) Axis Title" option and type in a
title - something like "Year" is sufficient. Do the same for the y-axis using a title with
appropriate units.
Note that different versions of Excel might have slight variations on how to accomplish the
assignment of axis titles. Ask someone for help if your version is different and you're not sure
how to get this done.
Heart Rate (bpm)
Exercise Experiment - Sally
160
140
120
100
80
60
40
20
0
0
20
40
60
Exercise Time (minutes)
80