Types of graphs

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Types of graphs
Level 1 Level 2
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Why do we use graphs?

• To display collected information (data) in a
  visual way
• Lots of information can be displayed in one graph
• To make things simpler.

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What are the most common types of graph?

• Line graph
• Bar chart
• Pie chart
• Pictogram
• Scatter graph or scatter plot.

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Other ways to show data

• In a list
• As a tally
• In a frequency table

Chocolate Vanilla Mint Pistachio Melon Fudge
8 8 4 3 6 1
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Line graph
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Line graph 2
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Bar chart
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Cumulative bar chart
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Comparative bar chart
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Bar graph 2 showing data for 2 years
www.dictionary.laborlawtalk.com/bar_chart
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Pie Chart
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So - what does a graph need?

• A title
• A label across (the x-axis)
• A label up the side (the y-axis)
• Numbers to show amounts (scale)
• Data plotted

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• Parts of a line graph or bar chart the
  essentials!

Graph Title
Y axis
Label for the y axis
X axis
Label for the x axis
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So - what does a pie chart need?

• A title
• A key (or legend)
• Data plotted as sectors (slices of the pie)

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Parts of a pie chart the essentials!
Sectors
A Key (legend)
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So - what does a pictogram need?

• A title
• A key (or legend)
• Minimum labelling (one axis only)
• Data plotted as graphics

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A very simple (edible) pictogram!
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Computer generated pictogram
www.kudlian.net
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So - what does a scatter graph need?

• A title
• A label across (the x-axis)
• A label up the side (the y-axis)
• Numbers to show amounts
• Two sets of bivariate data plotted
• Bivariate data is pairs of information from
  one source eg height and weight (growth chart)

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Scatter graph or plot
www.gifted.uconn.edu
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Scatter graph or plot
www.graphicsserver.com
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Which one to use

• Line graphs
• Observing trends over time
• Bar charts
• Seeing which is most/least
• Comparing one thing with another
• Pie charts
• Parts of a whole
• Data in percentages

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• Pictogram
• Potentially non-mathematical
• Easy to read
• Can simplify very large numbers
• Scatter graphs
• Paired data
• (height/weight mileage/age of car
  study/test results)

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Other graphs

• Frequency polygon
• A line on a graph joins the midpoints of
  histogram bars (looks like bar chart and line
  graph together)

www.gseis.ucla.edu
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Other graphs

• Block chart
• Similar to a bar chart but often simplified.
  Almost a bridge between bar chart and pictogram

www.elvethamheath.hants.sch.uk
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Useful words

• Frequency table
• A table with columns and rows showing the
  number of times an item or event occurs.

http//amazing-space.stsci.edu
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Useful words

• Tally, or bar gate
• A method of recording
• items using a mark, usually
• a line or stick.
• Tallies are recorded in
• sets of 5 for easy
• addition.

8
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Useful words

• Discrete data
• data resulting from a count of separate items
  or events, e.g. number of people, colours. On a
  bar chart the bars are separate.
• Continuous data
• data that can take any value e.g. height,
  temperature and time. On a bar chart the bars are
  next to each other.

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Useful words

• Axis
• X or horizontal axis
• Y or vertical axis

Y
X
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How are you doing?

• Think about these questions
• Do you feel confident with this topic?
• If you are not confident, re-run the slides.
• Or look for more on this topic in Section 10
  Graphs and Averages

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Credits

• Graphs generated in MS Excel unless stated on
  slide -
• See individual slides for URLs/photo credits
• GNU Free Documentation License

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