How will we plot this data?
Types of Graphs
Why Use a Graph?
• Put up a graph or a chart, and suddenly
everything you're saying makes sense!
– Graphs or charts help people understand data
quickly. Whether you want to make a
comparison, show a relationship, or highlight
a trend.
• They all look smart, but which one is
appropriate for the data you've collected?
Can you use a bar graph to show a trend? Is a line
graph appropriate for sales data? When do you use a
pie chart?
• Common graph types:
– Line graph- are most useful for showing trends, and
for identifying whether two variables relate to one
another.
– Bar graph-A type of graph that shows relationships
between different data series.
– Pie chart (circle graph)-A pie chart compares parts to
a whole. It shows a percentage distribution. The
entire pie represents the total data set and each
segment of the pie is a particular category within the
whole.
Line Graphs
• Examples of data you would plot as a line graph.
• Trends:
– How do sales vary from month to month?
– How does engine performance change as its
temperature increases?
• Correlation:
– On average, how much sleep do people get, based
on their age?
– Does the distance a child lives from school affect how
frequently he or she is late?
Line Graph- Sales by month
Bar Graph
• Another type of graph that shows
relationships between different data
related but not dependent on each other is
the bar graph.
– Here the height of the bar represents the
measured value.
– The higher or longer the bar, the greater the
value.
Bar Graph- sales of 3 products over 3 years
Pie Chart or Circle Graph
• Compares parts to a whole. As such it
shows a percentage distribution. The
entire pie represents the total data set and
each segment of the pie is a particular
category within the whole.
• The data you are measuring must show a
ratio or percentage relationship. You must
always use the same unit of measure
within a pie chart.
Example of Circle Graph- Where do
our sales come from?
What type of graph would you use
to plot this data?
• How far you drove over time.
• The mean height of 6th, 7th and 8th graders
• 7th grade students favorite type of pet by
percent.
• How you spend your time in a day..