DRAWING GRAPHS WITH EXCEL
LINE GRAPHS
1.
In this exercise you will learn how to draw line graphs using
Microsoft Excel, a spreadsheet program.
2.
You will also learn how to use the program to do some calculations,
such as working out the average from a set of data.
INSTRUCTIONS
Section 1
1.
Work in pairs, with a maximum of two people per computer.
2.
From the start button, select All Programs, then Microsoft Excel.
3.
This will open a blank spreadsheet page called Book 1. This page
consists of a large number of cells into which we can enter
information. These cells run in rows across the page and columns up
and down the page. Each cell has a unique identity, e.g. the first cell is
A1, the next one down A2, etc.
4.
Imagine we want to draw a graph of how the temperature in a place
changes over a year. Using the table on the next page, enter the
information shown. Do this very carefully, but if you make a mistake,
don’t worry, simply clear the mistake by using the backspace key in
the cell itself, or in the Insert Function panel – see the screenshot
below.
Cell A1
Insert Function panel
1
5.
Transfer these figures of average monthly temperature into your
spreadsheet. They show the temperature each month in a place in
Siberia, the coldest inhabited area in the world. See the screenshot
below the table to see what to do if you are not sure.
Month
Temperature
J
-18
F
-16
M
-13
A
-3
Enter
data like
this.
M
11
J
19
Jl
22
A
19
S
14
O
4
N
-7
D
-15
Chart
Wizard
Highlight a column by clicking the
letter at the top of the column, or by
clicking on a cell and dragging the
cursor across the cells involved.
Note: You can enter data in the spreadsheet vertically,
as above, or horizontally. In this example you
could use the first two rows or the first two columns.
6.
Highlight the data, then click on the Chart Wizard button and select
Line from the Standard Types. Make sure the first type of graph on
the second row is selected, and then click Next.
Select Line from
the options given,
select the type of
graph shown
here, then click
Next.
2
7.
You should now see this
graph. Click Next to continue.
8.
Now give the graph a
title (Average Monthly
Temperatures in
Siberia) and add the
words Month and
Degrees Celsius in the
windows shown.
9.
On the same screen click on the Legend tab and clear the Show
legend box.
Show legend box
3
10.
Also on the same screen, click on the Data Table tab and tick the
Show data table box. See what happens to the graph – the monthly
figures are shown below the graph line. Then click Next.
Show data
table box
11.
Select As new sheet; then click Finish.
12.
Your temperature graph should now look like this.
4
Section 2 – Calculations
13.
Now we will use the spreadsheet to do some simple calculations. First
of all go back to the spreadsheet using the Sheet 1 button shown
below.
Sheet 1 button.
14.
Highlight your data; then select Average from the drop-down menu
beside the AutoSum symbol, which looks like this:
1. Highlight
your data.
2. Click on the
small arrow;
then select
Average from
the drop-down
menu.
The average of the twelve monthly temperatures will be shown in the next
cell down. (1.416667 degrees Celsius!) Now try the same for Max and Min
– it's easy to see from the data what these values are this time, but more
difficult when you have lots and lots of similar figures.
Note: You shouldn’t really use the Sum command with line graphs, because
line graphs usually show a gradual change or trend in something, not
something which can be added up. For example, adding up twelve months'
worth of temperatures doesn’t really make much sense.
5
Section 3 – When is a number not a number?
15.
A problem with spreadsheet programs is that they can be confused by
certain numbers! Dates, in particular, can be misread by the computer,
which thinks they are just another number, and this can lead to strange
looking results. As we use dates a lot when drawing line graphs in
Geography, we have to get round this problem.
16.
In the spreadsheet below, we have entered data for the world’s
population between the years 1650 and 2050. The data in the first
column of figures are clearly dates, but the computer doesn’t know
this, so we have to fool it a little! Two methods are shown below.
Either
Before you add any
data, highlight the
cells which are to
contain dates; select
Format, then Cells,
then Text (from the
Number tab).
Or – leave
the first
row blank.
Chart button
Or – an alternative way is to proceed
as before, but leave the first row
blank, then highlight the data only
(not the blank cells), click on the
Chart button, select Line from the
Standard Types and click Next.
17.
You should
now see this –
click on Next to
continue.
6
18.
With the Titles
button selected,
add the labels
shown below;
then select the
Legend tab and
clear the Show
legend box and,
finally, click
Next.
19.
Select As new sheet and then click Finish.
20
Nearly there! Your graph should now look like this – but the dates are
not quite in the correct position.
Double
click on the
white
border of
the graph,
near the
dates.
21.
This window will appear –
Select Outside in
the Minor tick
mark type options;
then OK.
7
28.
At last – the completed graph!
Want to try some advanced techniques?
TOP TIP – place your cursor arrow exactly on the feature you wish to
change and double click the left mouse button (or right click, then left click)
to open up a new screen which allows you to make the changes. This is
difficult, so concentrate and be prepared to get there by trial and error!
Your final challenge is to change the appearance of this graph, so that:
(i) the background colour becomes white; (left mouse button, double click);
(ii) the colour of the line changes to red; and gets thicker (left mouse
button, double click);
(iii) the line is smoothed (left mouse button, double click);
(iv) you get rid of the markers (left mouse button, double click);
(v) you change the y axis scale to show major tick marks every 1 billion,
rather than every 2, with minor tick marks each 0.5 billion (very
difficult!!!). Try using the Scale and Patterns tabs in the Format Axis
window.
8
Further Work
Here are some other exercises to try – to create some of these graphs
you may have to read some sections of this guide again – or find out for
yourself by searching on the spreadsheet toolbars and drop-down menus.
1.
Draw a simple line graph to show these readings of river velocity at
different places along a local river.
Velocity
(m/sec)
2.
Site 1
Site 2
Site 3
Site 4
Site 5
Site 6
Site 7
Site 8
Site 9
Site 10
0.4
0.6
0.9
1.3
1.6
2.2
2.8
3.5
4.2
4.6
Draw a line graph to show these figures for average milk yield for
cows in Scotland: do you remember what to do with dates?
Year
Milk
Yield
(litres)
1944
1954
1964
1974
1984
1994
2400
3200
3500
3500
5000
5300
(The Human Environment, C. Clarke, page 96)
3.
Draw a multiple line graph to show these maximum and minimum
temperatures in Glasgow in August 1977. No clues – you find out how
to do it!
Day 21
22
23
24
25
26
27
28
29
30
31
Max 22
21
19
17
21
21
19
19
18
19
19
Min 18
13
9
9
12
9
14
10
9
7
9
(The Physical Environment, C. Clarke, page 12)
9