The Different Types of Charts
Area Chart Figure 1: Area chart
Use it to... * Display over time (or any other dimension): * How a set of data adds up to a whole (cumulated totals) * Which part of the whole each element represents
Variants
* Percentage: The sum always represents 100% (relative scale) * Cumulative: The sum can vary according to the elements (absolute scale)
Column/Bar Chart
Use it to... * Present few data over a nominal (e.g. countries, testing conditions, ...) or interval scale (e.g. time); useful for comparisons of data
Do not Use it for... * Comparisons: Better use one-dimensional scatterplots, because these are not dominated by bars or columns. * Larger data sets: Use line charts.
Selecting Bars or Columns * Use analogy as a selection criterion, if applicable; when in doubt, use columns * Use a horizontal bar chart if the labels are too long to fit under the columns
Variants
* Multiple Column/Bar Chart: Use it to present data rows for several variables * Side-by-Side Chart: Use it to (1) show contrasting trends between levels of an independent variable, (2) if comparisons between individual pairs of values are most important; do not use for more than two independent variables | | |
Figure 2: Multiple column chart (left), side-by-side chart (right)
Segmented Column/Bar Chart
Other Names: Divided or stacked column/bar chart
Figure 3: Segmented column chart (relative values)
Use it to... * Present a part-whole relation over time (with accurate impression, see below) * Show proportional relationships over time * Display wholes which are levels on a nominal scale
Segmented column/bar charts are more accurate than pie chart, because distances can be more accurately estimated than areas.
Frequency Polygon, Histograms
Figure 4: Histogram as frequency distribution
Variants
* Polygon: Connects data points through straight lines or higher order graphs * Histogram: Columns/bars
Use it to... * Display over time (or any other dimension): * How a set of data adds up to a whole (cumulated totals) * Which part of the whole each element represents
Variants
* Percentage: The sum always represents 100% (relative scale) * Cumulative: The sum can vary according to the elements (absolute scale)
Column/Bar Chart
Use it to... * Present few data over a nominal (e.g. countries, testing conditions, ...) or interval scale (e.g. time); useful for comparisons of data
Do not Use it for... * Comparisons: Better use one-dimensional scatterplots, because these are not dominated by bars or columns. * Larger data sets: Use line charts.
Selecting Bars or Columns * Use analogy as a selection criterion, if applicable; when in doubt, use columns * Use a horizontal bar chart if the labels are too long to fit under the columns
Variants
* Multiple Column/Bar Chart: Use it to present data rows for several variables * Side-by-Side Chart: Use it to (1) show contrasting trends between levels of an independent variable, (2) if comparisons between individual pairs of values are most important; do not use for more than two independent variables | | |
Figure 2: Multiple column chart (left), side-by-side chart (right)
Segmented Column/Bar Chart
Other Names: Divided or stacked column/bar chart
Figure 3: Segmented column chart (relative values)
Use it to... * Present a part-whole relation over time (with accurate impression, see below) * Show proportional relationships over time * Display wholes which are levels on a nominal scale
Segmented column/bar charts are more accurate than pie chart, because distances can be more accurately estimated than areas.
Frequency Polygon, Histograms
Figure 4: Histogram as frequency distribution
Variants
* Polygon: Connects data points through straight lines or higher order graphs * Histogram: Columns/bars