Types of Graph

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Types of Graph

• And when to use them!

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Line Graph
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Line Graph

• Used to show trends
• Variable plotted on X (bottom) musts be
  continuous
• Common type is time series where X time
• CANNOT be used to graph data where X is discrete

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Scatterplot
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Scatterplot

• Used to show relationships between variables
• X variable must be continuous
• If one variable is believed to cause or explain
  changes in the other, that variable is plotted on
  the X

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Bar Graph
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Bar Graph

• Used to compare amounts or frequencies in data
  that represents different categories (discrete
  data sets)
• Categorical data set is plotted on X,
  quantitative (continuous) on the Y
• Often used incorrectly to graph data with
  continuous X variables

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Histogram
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Histogram

• Used when discrete X is converted to categories
  (bins)
• Y represents frequency of data within each bin

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Pie Chart
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Pie Chart

• Used for same kind of data as bar chart
• Each slice data category
• Slice size shows relative proportion of
  observations within each category

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Summary Types of Graph
Graph type Use
Line graph Connects dots with lines Used for continuous X data Show patterns or trends If time X, time-series graph
Scatterplot Display/assess relationship between variables
Bar graph Used to show patterns Should only be used when X data are categorical
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Graph type Description
Histogram Similar to bar graph, but used when continuous X data are converted to categories
Pie chart Compares small number of categories. Works best if values are very different. If similar, should label pie segments with actual values