Main Resource: Statistics Canada
You have probably heard of the term the
information age. It describes how modern
society depends on information as a
resource. People rely on information to make
decisions and recommendations in many
fields, including politics, economics,
environment and entertainment.
Without reliable information, people can
make poor decisions that sometimes result in
Since the media plays an immense part in our
daily life and they are continually giving us
Data analysis is often used in advertising,
forecasting, and public policy. The media is full
of representations of data (i.e. Graphs or tables)
to support statistical claims.
We need to be critical to:
Know what is relevant
Know what is important
Know what is true
Know what is biased
A graph is a visual representation of a
relationship between, but not restricted to,
Graphs are effective visual tools because
they present information quickly and easily.
It is not surprising then, that graphs are
commonly used by print and electronic
Double bar graphs
A circle graph displays data as a percentage
of the whole. Each pie section should have a
label and percentage. A total data number
should be included.
A line graph plots continuous data as points
and then joins them with a line. Multiple
data sets can be graphed together, but a key
must be used.
A bar graph displays discrete data in separate
columns. A double bar graph can be used to
compare two data sets. Categories are
considered unordered and can be rearranged
alphabetically, by size, etc.
A pictograph uses an icon to represent a
quantity of data values in order to decrease
the size of the graph. A key must be used to
explain the icon.
Misinterpretation is a common problem when
using statistical information. It may be
caused by a number of factors.
Misunderstanding the data
Using incomparable definitions
Deliberately misinterpreting the information
In groups of 2 or 3, come get a worksheet
and answer the questions.
You will need to prepare a short presentation
about your topic (based on your worksheet)
to present to the class.
Shows percent of total for each category
No exact numerical data
Hard to compare 2 data sets
"Other" category can be a problem
Total unknown unless specified
Best for 3 to 7 categories
Use only with discrete data
Can compare multiple continuous data sets easily
Interim data can be inferred from graph line
Use only with continuous data
Can easily compare two or three data sets
Graph categories can be reordered to emphasize
Use only with discrete data
Easy to read
Handles large data sets easily using keyed icons
Hard to quantify partial icons
Icons must be of consistent size
Best for only 2-6 categories
Look at the effect of not starting
the y-axis of 0.
It is important to start graphs at
Look at this pictograph. It looks like there are more horses. It is
important that all the pictures are the same size.
Why does Graph A look different than Graph B? Both the
graphs represent the same data.
The graphs look different due to the
different vertical scales. Graph A appears
to show a more rapid decrease in sales
than graph B.