Create a Box Plot from a Five-Number Summary

[#1]

Problem

Instead of a full data set, you have a summarized version that contains the five numbers needed to define a box plot.

Solution

You can use frequencies to mimic a full data set based on the five-number summary. If you enter the five data points in a data table and then create a second column with frequencies that force your data points to be at the appropriate quantiles, you can use that data table as if it were the raw data. For a box plot with endpoints at the 5% and 95% quantiles, you could use the five-point summary 3, 15, 20, 40, 42 with frequencies of 5, 20, 25, 25, and 20, respectively. The following JSL gives an example:

Names Default To Here( 1 );
dt = New Table( "Boxplot",
	Add Rows( 5 ),
	New Column( "Summary Point",
		Numeric,
		"Continuous",
		Format( "Best", 18 ),
		Set Values( [3, 15, 20, 40, 42] )
	),
	New Column( "Freq",
		Numeric,
		"Continuous",
		Format( "Best", 18 ),
		Set Values( [5, 20, 25, 25, 20] )
	)
);

dt << Graph Builder(
	Variables( Y( :Summary Point ), Frequency( :Freq ) ),
	Elements( Box Plot( Y, Legend( 7 ) ) )
);

Discussion

The summarized values above are for illustration purposes and can be replaced by other values.

See Also

Discussion Post