There are different types of diagrams you can use to display discrete data. Each type has advantages and disadvantages. You need to consider which one is most appropriate for the data you have.
Diagram
Advantages
Disadvantages
Bar chart
Simple to draw
Easy to understand
Can be used for both quantitative and qualitative data
Only simple information can be shown
Multiple bar chart
Data can be easily compared
Only a few categories can be compared.
Sometimes confusing to read.
Pie chart
Good visual for displaying data with only a few categories
Original data is difficult to read from the chart
Pictogram
Excellent visual for displaying qualitative data
Not good for quantitative data
Difficult to read part symbols
NOTE For coursework, you must use ICT to produce graphs.
Production of Bar charts and pie charts is covered in ICT classes.
A class was asked their favourite colour. A bar chart was then constructed.
Colour
Red
Blue
Green
Purple
Black
Pink
Yellow
Frequency
6
6
5
4
4
6
1
The data was then divided into favourite male/female colours and a multiple bar chart was drawn.
Colour
Red
Blue
Green
Purple
Black
Pink
Yellow
Male numbers
4
5
2
1
3
0
1
Female numbers
2
1
3
3
1
6
0
Example of pie chart
Table to show holiday destinations chosen for Access ‘Holiday’ coursework
UK
Ireland
Spain
Italy
USA
France
Other
12
5
28
16
9
8
4
Make sure that the colours of the sectors can be differentiated between when printing in black and white.
Pictograms
A pictogram is a simple way of representing data by using pictures (or some other representation) to show the data. A pictogram must have a key to tell the reader what individual pictures stand for.
Example
The table shows the number of people entering an exhibition on different days of the week.
Day
Thursday
Friday
Saturday
Sunday
Frequency
22
27
33
21
NOTE - It is difficult to read partial pictures
Instructions for drawing a pictogram using ICT
Draw a horizontal bar chart (as below). Right click on any bar. Then choose ‘Insert’, then ‘picture’ and then ‘clip art’. Choose an appropriate image. This will replace the bar by one image.
Right click again on the bar.
Choose ‘Format Data Series’.
Select ‘Fill effects’. Choose ‘Stack and scale’. The above pictogram has selected ‘5’.
NOTE – Instructions may vary depending on the computer package you are using.
Exercise 1
Use ICT to produce the following graphs.
1. The table shows the number of washing machines sold over a six month period. Month
May
Jun
Jul
Aug
Sep
Oct
Number sold
40
45
90
80
35
25
Show this data on a pictogram.
2. Students were asked how they traveled to college.
Method of travel
Car
Bus
Train
Motorbike
Walk
Other
Frequency
32
79
8
27
32
6
Show this information in a bar chart.
3. The population (in Millions) of California by ethnic group is given in the following table.
White
Hispanic
Black
Other
1980
16.8
3.8
1.8
1.3
1990
17.9
6.4
1.8
3.5
2000
16.0
7.5
2.0
8.5
Present this information in a multiple bar chart. Comment on your chart.
4. Students were surveyed about their favourite type of food. The results are in the table below. Type of food
British
Chinese
Indian
Italian
Mexican
Other
Frequency
34
29
16
48
9
12
Illustrate this information in a pie chart.
5. The table below shows the number of patients who attended morning and afternoon surgery at a clinic.
Remember that continuous data is usually collected in groups, so most of these diagrams use groups to display the data.
Frequency diagrams and frequency polygons
A frequency diagram is similar to a bar chart but the bars are drawn with no gaps as they represent continuous data. The axis will have a continuous scale.
A frequency polygon joins the mid-points of the bars of a frequency diagram. You must include a group both at
