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The UNIVARIATE Procedure

Example 4.18 Binning a Histogram

This example, which is a continuation of Example 4.14, demonstrates various methods for binning a histogram. This example also illustrates how to save bin percentages in an OUTHISTOGRAM= data set.

The manufacturer from Example 4.14 now wants to enhance the histogram by using the ENDPOINTS= option to change the endpoints of the bins. The following statements create a histogram with bins that have end points 3.425 and 3.6 and width 0.025:

title 'Enhancing a Histogram';
ods select HistogramBins MyHist;
proc univariate data=Trans;
   histogram Thick / midpercents name='MyHist'
                     endpoints = 3.425 to 3.6 by .025;

The ODS SELECT statement restricts the output to the "HistogramBins" table and the "MyHist" histogram; see the section ODS Table Names. The ENDPOINTS= option specifies the endpoints for the histogram bins. By default, if the ENDPOINTS= option is not specified, the automatic binning algorithm computes values for the midpoints of the bins. The MIDPERCENTS option requests a table of the midpoints of each histogram bin and the percent of the observations that fall in each bin. This table is displayed in Output 4.18.1; the histogram is displayed in Output 4.18.2. The NAME= option specifies a name for the histogram that can be used in the ODS SELECT statement.

Output 4.18.1 Table of Bin Percentages Requested with MIDPERCENTS Option
Enhancing a Histogram

The UNIVARIATE Procedure

Histogram Bins for
3.425 8.000
3.450 21.000
3.475 25.000
3.500 29.000
3.525 11.000
3.550 5.000
3.575 1.000

Output 4.18.2 Histogram with ENDPOINTS= Option
Histogram with ENDPOINTS= Option

The MIDPOINTS= option is an alternative to the ENDPOINTS= option for specifying histogram bins. The following statements create a histogram, shown in Output 4.18.3, which is similar to the one in Output 4.18.2:

title 'Enhancing a Histogram';
proc univariate data=Trans noprint;
   histogram Thick / midpoints    = 3.4375 to 3.5875 by .025
                     outhistogram = OutMdpts;

Output 4.18.3 differs from Output 4.18.2 in two ways:

Output 4.18.3 Histogram with MIDPOINTS= and RTINCLUDE Options
Histogram with MIDPOINTS= and RTINCLUDE Options

The OUTHISTOGRAM= option produces an output data set named OutMdpts, displayed in Output 4.18.4. This data set provides information about the bins of the histogram. For more information, see the section OUTHISTOGRAM= Output Data Set.

Output 4.18.4 The OUTHISTOGRAM= Data Set OutMdpts
Enhancing a Histogram

1 Thick 3.4375 9 9
2 Thick 3.4625 21 21
3 Thick 3.4875 26 26
4 Thick 3.5125 28 28
5 Thick 3.5375 11 11
6 Thick 3.5625 5 5

A sample program for this example,, is available in the SAS Sample Library for Base SAS software.

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