SIMSYSTEM Procedure

PROC SIMSYSTEM Statement

PROC SIMSYSTEM <options>;

The PROC SIMSYSTEM statement invokes the SIMSYSTEM procedure. Table 1 summarizes the options available in the PROC SIMSYSTEM statement.

Table 1: PROC SIMSYSTEM Statement Options

Option	Description
CDF=	Specifies values at which to compute the cumulative probability
DATA=	Specifies an input CAS data table
MOMENTREPS	Displays moments of individual sample replicates
N=	Specifies the number of values to sample
NOPRINT	Suppresses the normal display of results
NREP=	Specifies the number of sample replicates
PDF=	Specifies values at which to compute the probability density
PLOTS	Controls the plots that are produced through ODS Graphics
QUANTILE=	Specifies quantiles of the distribution to be computed
SEED=	Specifies the seed for pseudorandom number generation
SIMPLETOL=	Specifies the tolerance value for choosing a simpler distribution
SYSTEM=	Specifies the system of distributions to sample from

You can specify the following options:

CDF=values

specifies values at which to compute the exact cumulative probability for each distribution. The computed cumulative probabilities are included as nonprinting columns in the table of distribution parameters.

DATA=libref.data-table

names the input data table for PROC SIMSYSTEM to use. libref.data-table is a two-level name, where

libref: refers to a collection of information that is defined in the LIBNAME statement and includes the library, which includes a path to the data, and a session identifier, which defaults to the active session but which can be explicitly defined in the LIBNAME statement. For more information about libref, see the section Using CAS Sessions and CAS Engine Librefs.
data-table: specifies the name of the input data table.

This data table must contain a numeric variable named Skewness and a numeric variable named Kurtosis. The data table can also contain the following numeric variables:

Mean, which contains the mean values of the distributions to be simulated
StdDev, which contains the standard deviation values of the distributions to be simulated
SimIndex, which contains simulation indexes that identify the distributions in output tables and data tables

If you specify this option, then you cannot use the MOMENTS statement or the MOMENTGRID statement.

MOMENTREPS MREPS

displays sample moments for individual samples when multiple replicates are computed by using the NREP= option.

N=value

specifies the number of simulated values to compute for each distribution. By default, N=0; that is, if you omit this option, then no samples are computed.

NOPRINT

suppresses the normal display of results. This option temporarily disables the Output Delivery System (ODS).

NREP=value

specifies the number of sample replicates to compute for each distribution. If you specify a value larger than 1, then PROC SIMSYSTEM displays the sample moments averaged over the replicates instead of displaying the sample moments. If you still want to see the moments for individual samples, use the MOMENTREPS option.

By default, NREP=1.

PDF=values

specifies values at which to compute the exact probability density function for each distribution. The computed PDF values are included as nonprinting columns in the table of distribution parameters.

QUANTILE=values

specifies probability values at which to compute the exact quantiles for each distribution, where each of the specified values must be between 0 and 1, inclusive. The computed quantiles are included as nonprinting columns in the table of distribution parameters.

PLOTS <(global-plot-options)> <=plot-request <(options)>> PLOTS <(global-plot-options)> <=(plot-request <(options)> <…plot-request <(options)>>)>

controls the plots produced through ODS Graphics. When you specify only one plot-request, you can omit the parentheses around the plot-request. The following examples show a variety of ways that you can specify this option:

   PLOTS=NONE
   PLOTS=(MRMAP HISTOGRAM)
   PLOTS(UNPACK)=HISTOGRAM
   PLOT=MRMAP(SKEWSCALE=SQUARE)

ODS Graphics must be enabled before plots can be requested, as shown in the following example:

ods graphics on;
proc simsystem n=100 seed=12345;
   momentgrid skew=1.5 kurt=7;
   output out=mylib.sim;
run;
ods graphics off;

If ODS Graphics is enabled but you do not specify the PLOTS= option, then PROC SIMSYSTEM produces a moment-ratio map (PLOT=MRMAP) by default and also a histogram of the centered and scaled sample values. If multiple distributions are being sampled, then the histogram for each one is displayed by default in a lattice.

You can specify the following global-plot-options:

ONLY: suppresses the default plots. Only plots that you specifically request are displayed.
UNPACKPANEL UNPACK: suppresses paneling. By default, multiple histograms can appear in an output panel. Specify this option to display each plot in a separate panel.

You can specify the following individual plot-requests and their plot-options. If you specify only one plot-request, then you can omit the parentheses.

ALL

produces all appropriate plots. You can specify other options by using ALL; for example, to request all plots and unpack only the histogram lattices, specify PLOTS=(ALL HISTOGRAM(UNPACK)).

HISTOGRAM<(UNPACK)>

modifies the histograms of sampled values. By default, histograms of multiple distributions are displayed together in a panel. The UNPACK suboption suppresses their display in a panel and instead produces the series of individual plots that form the paneled display.

MRMAP<(INDEXLABELS)>

modifies the moment-ratio map. The specified distributions are marked on the map by using their simulation index values instead of the default marker.

MRMAP<(KURTSCALE=DIRECT | REVERSE)>

modifies the moment-ratio map. You can specify the following values for the KURTSCALE= suboption:

DIRECT: displays the kurtosis values in increasing order from bottom to top.
REVERSE: displays the kurtosis values in reverse order, increasing from top to bottom.

By default, KURTSCALE=REVERSE.

MRMAP<(SKEWSCALE=ABS | SKEWNESS | SQUARE)>

modifies the moment-ratio map. You can specify the following values for the SKEWSCALE= suboption:

ABS: displays the absolute value of skewness.
SKEWNESS: displays the skewness.
SQUARE: displays the square of the skewness.

By default, SKEWSCALE=ABS.

NONE

suppresses all graphics.

SEED=n

specifies an integer to use to start the pseudorandom number generator for drawing samples. If you do not specify a seed or if you specify a value less than or equal to 0, the seed is generated by reading the time of day from the computer’s clock.

SIMPLETOL=n

specifies a tolerance value to use in choosing to map input skewness and kurtosis values to those of a simpler distribution. For more information about how this value is used, see Specifying Boundary Widths for Transition Families. The default value for n is .

SYSTEM=PEARSON | JOHNSON

specifies the system to use to simulate data. You can specify the following values:

JOHNSON: uses the Johnson system (Johnson 1949).
PEARSON: uses the Pearson system (Pearson 1895, 1901, 1916).

By default, SYSTEM=PEARSON. For more information about the Johnson and Pearson systems, see Details: SIMSYSTEM Procedure.

Last updated: June 22, 2026