Histogram

Use Histogram to examine the shape and spread of your data. A histogram works best when the sample size is at least 20.

In This Topic

Continuous variables
Layout
Group variable
By variables
Y-scale

For information about data considerations, examples, and interpretation, go to Overview for Histogram.

Continuous variables

Enter one or more numeric columns that you want to graph.

Layout

Choose one of the following layout options.

Separate graphs for each continuous variable: Creates a separate histogram for each column in the Continuous variables field.
Overlay continuous variables: Columns in the Continuous variables field are overlaid on a single histogram.

Group variable

Enter a variable that defines the groups. Group labels are shown in the graph legend.

By variables

Enter one or more grouping variables in By variables to create a separate histogram for each level of the grouping variables. The columns that you enter must be the same length as the columns in Continuous variables. The y-scales for each variable are the same across the multiple histograms.

Show all combinations

When you enter multiple By variables, Minitab enables the Show all combinations checkbox. Select this option to create a separate histogram for each combination of groups created by the By variables. If you do not select this option, Minitab creates a plot for each group of each By variable.

For example, the first By variable has 2 groups, Male and Female, and the second By variable has 2 groups, Employed and Unemployed. If you select Show all combinations, Minitab creates 4 separate plots for the combinations of Male/Employed, Male/Unemployed, Female/Employed, and Female/Unemployed. If you do not select Show all combinations, Minitab creates 4 separate plots for Male, Female, Employed, and Unemployed.

Y-scale

Select how you want to display the y-scale.

Frequency: The height of each bar represents the number of observations that fall within the bin of a histogram.
Percent: The height of each bar represents the percentage of the sample observations that fall within the bin. A histogram with a percentage scale is sometimes called a relative frequency histogram. Use a percent scale to compare samples of different sizes.

Same Y-scale

Make the Y-scale the same across multiple graphs.

Same X-scale

Make the X-scale the same across multiple graphs.