Dictionary of Options

PPPLOT Statement

Dictionary of Options

The following entries provide detailed descriptions of options for the PPPLOT statement.

ALPHA=value

specifies the shape parameter $\alpha$ $(\alpha\gt)$ for P-P plots requested with the BETA and GAMMA options. For examples, see the entries for the BETA and GAMMA options.

ANNOTATE=SAS-data-set

ANNO=SAS-data-set

[Graphics]
specifies an input data set containing annotate variables as described in SAS/GRAPH Software: Reference. You can use this data set to add features to the plot. The ANNOTATE= data set specified in the PPPLOT statement is used for all plots created by the statement. You can also specify an ANNOTATE= data set in the PROC CAPABILITY statement to enhance all plots created by the procedure; for more information, see "ANNOTATE= Data Sets".

BETA<(beta-options)>

creates a beta P-P plot. To create the plot, the n nonmissing observations are ordered from smallest to largest:

The y-coordinate of the i^th point is the empirical cdf value [i/n]. The x-coordinate is the theoretical beta cdf value


		 
 
where  is the normalized incompletebeta function, , and 
 
		  lower threshold parameter
		  scale parameter  
		  first shape parameter  
		  second shape parameter

You can specify $\alpha$ , $\beta$ , $\sigma$ , and $\theta$ with the ALPHA=, BETA=, SIGMA=, and THETA= beta-options, as illustrated in the following example:

   proc capability data=measures;
      ppplot width / beta(theta=1 sigma=2 alpha=3 beta=4);
   run;

If you do not specify values for these parameters, then by default, $\theta=0$ , $\sigma=1$ , and maximum likelihood estimates are calculated for $\alpha$ and $\beta$ .

IMPORTANT: If the default unit interval (0,1) does not adequately describe the range of your data, then you should specify THETA= $\theta$ and SIGMA= $\sigma$ so that your data fall in the interval $(\theta, \theta+\sigma)$ .

If the data are beta distributed with parameters $\alpha$ , $\beta$ , $\sigma$ , and $\theta$ , then the points on the plot for ALPHA= $\alpha$ , BETA= $\beta$ , SIGMA= $\sigma$ , and THETA= $\theta$ tend to fall on or near the diagonal line y=x, which is displayed by default. Agreement between the diagonal line and the point pattern is evidence that the specified beta distribution is a good fit. You can specify the SCALE= option as an alias for the SIGMA= option and the THRESHOLD= option as an alias for the THETA= option.

BETA=value

specifies the shape parameter $\beta$ $(\beta \gt)$ for P-P plots requested with the BETA distribution option. See the preceding entry for the BETA distribution option for an example.

C=value

specifies the shape parameter c (c>0) for P-P plots requested with the WEIBULL option. See the entry for the WEIBULL option for examples.

CAXIS=color

CAXES=color

[Graphics]
specifies the color for the axes. This option overrides any COLOR= specifications in an AXIS statement. The default is the first color in the device color list.

CFRAME=color

CFR=color

[Graphics]
specifies a fill color for the area enclosed by the axes and frame. By default, this area is not filled.

CHREF=color

CH=color

[Graphics]
specifies the color for reference lines requested by the option. The default is the first color in the device color list.

COLOR=color

[Graphics]
specifies the color for the diagonal reference line. For example, the following statements request a blue line:

   proc capability data=measures;
      ppplot length / normal(mu=10 sigma=0.25 color=blue);
   run;

The default is the first color in the device color list.

CTEXT=color

[Graphics]
specifies the color for tick mark values and axis labels. The default is the color specified for the CTEXT= option in the most recent GOPTIONS statement.

CVREF=color

CV=color

[Graphics]
specifies the color for reference lines requested by the VREF= option. The default is the first color in the device color list.

DESCRIPTION='string'

DES='string'

[Graphics]
specifies a description, up to 40 characters, that appears in the PROC GREPLAY master menu. The default string is the variable name.

EXPONENTIAL<(exponential-options)>

EXP<(exponential-options)>

creates an exponential P-P plot. To create the plot, the n nonmissing observations are ordered from smallest to largest:

The y-coordinate of the i^th point is the empirical cdf value [i/n]. The x-coordinate is the theoretical exponential cdf value


		 
 
where 
 
		  threshold parameter
		  scale parameter

You can specify $\sigma$ and $\theta$ with the SIGMA= and THETA= exponential-options, as illustrated in the following example:

   proc capability data=measures;
      ppplot width / exponential(theta=1 sigma=2);
   run;

If you do not specify values for these parameters, then by default, $\theta=0$ and a maximum likelihood estimate is calculated for $\sigma$ .

IMPORTANT: Your data must be greater than or equal to the lower threshold $\theta$ . If the default $\theta=0$ is not an adequate lower bound for your data, specify $\theta$ with the THETA= option.

If the data are exponentially distributed with parameters $\sigma$ and $\theta$ , the points on the plot for SIGMA= $\sigma$ and THETA= $\theta$ tend to fall on or near the diagonal line y=x, which is displayed by default. Agreement between the diagonal line and the point pattern is evidence that the specified exponential distribution is a good fit. You can specify the SCALE= option as an alias for the SIGMA= option and the THRESHOLD= option as an alias for the THETA= option.

FONT=font

[Graphics]
specifies a software font for horizontal and vertical reference line labels and axis labels. You can also specify fonts for axis labels in an AXIS statement. The FONT= font takes precedence over the FTEXT= font you specify in the GOPTIONS statement. Hardware characters are used by default.

GAMMA<(gamma-options)>

creates a gamma P-P plot. To create the plot, the n nonmissing observations are ordered from smallest to largest:

The y-coordinate of the i^th point is the empirical cdf value [i/n]. The x-coordinate is the theoretical gamma cdf value


		 
 
where  is the normalized incompletegamma function, and 
 
		  threshold parameter
		  scale parameter  
		  shape parameter

You can specify $\alpha$ , $\sigma$ , and $\theta$ with the ALPHA=, SIGMA=, and THETA= gamma-options, as illustrated in the following example:

   proc capability data=measures;
      ppplot width / gamma(alpha=1 sigma=2 theta=3);
   run;

If you do not specify values for these parameters, then by default, $\theta=0$ and maximum likelihood estimates are calculated for $\alpha$ and $\sigma$ .

IMPORTANT: Your data must be greater than or equal to the lower threshold $\theta$ . If the default $\theta=0$ is not an adequate lower bound for your data, specify $\theta$ with the THETA= option.

If the data are gamma distributed with parameters $\alpha$ , $\sigma$ , and $\theta$ , the points on the plot for ALPHA= $\alpha$ ,SIGMA= $\sigma$ , and THETA= $\theta$ tend to fall on or near the diagonal line y=x, which is displayed by default. Agreement between the diagonal line and the point pattern is evidence that the specified gamma distribution is a good fit. You can specify the SHAPE= option as an alias for the ALPHA= option, the SCALE= option as an alias for the SIGMA= option, and the THRESHOLD= option as an alias for the THETA= option.

HAXIS=name

[Graphics]
specifies the name of an AXIS statement describing the horizontal axis.

HMINOR=n

HM=n

[Graphics]
specifies the number of minor tick marks between each major tick mark on the horizontal axis. Minor tick marks are not labeled. The default is 0.

HREF=value-list

draws reference lines perpendicular to the horizontal axis at the values specified. See also the HREFCHAR=, CHREF=, and LHREF=options.

HREFCHAR='character'

[Line Printer]
specifies the character used to form the reference lines requested by the HREF=option for a line printer. The default is the vertical bar (|).

HREFLABELS='label1' ... 'labeln'

HREFLABEL='label1' ... 'labeln'

HREFLAB='label1' ... 'labeln'

specifies labels for the reference lines requested by the HREF=option. The number of labels must equal the number of lines. Enclose each label in quotes. Labels can be up to 16 characters.

L=linetype

[Graphics]
specifies the line type for the diagonal distribution reference line. For example,

   proc capability data=measures;
      ppplot length / normal(mu=10 sigma=0.25 l=2);
   run;

The default is 1, which produces a solid line.

LHREF=linetype

LH=linetype

[Graphics]
specifies the line type for reference lines requested by the HREF=option. The default is 2, which produces a dashed line.

LOGNORMAL<(lognormal-options)>

LNORM<(lognormal-options)>

creates a lognormal P-P plot. To create the plot, the n nonmissing observations are ordered from smallest to largest:

The y-coordinate of the i^th point is the empirical cdf value [i/n]. The x-coordinate is the theoretical lognormal cdf value


		 
 
where  is the cumulative standard normaldistribution function, and 
 
		  threshold parameter
		  scale parameter
		  shape parameter

You can specify $\theta$ , $\zeta$ , and $\sigma$ with the THETA=, ZETA=, and SIGMA= lognormal-options, as illustrated in the following example:

   proc capability data=measures;
      ppplot width / lognormal(theta=1 zeta=2);
   run;

If you do not specify values for these parameters, then by default, $\theta=0$ and maximum likelihood estimates are calculated for $\sigma$ and $\zeta$ .

IMPORTANT: Your data must be greater than the lower threshold $\theta$ . If the default $\theta=0$ is not an adequate lower bound for your data, specify $\theta$ with the THETA= option.

If the data are lognormally distributed with parameters $\sigma$ , $\theta$ , and $\zeta$ , the points on the plot for SIGMA= $\sigma$ ,THETA= $\theta$ , and ZETA= $\zeta$ tend to fall on or near the diagonal line y=x, which is displayed by default. Agreement between the diagonal line and the point pattern is evidence that the specified lognormal distribution is a good fit. You can specify the SHAPE= option as an alias for the SIGMA=option, the SCALE= option as an alias for the ZETA= option, and the THRESHOLD= option as an alias for the THETA= option.

LVREF=linetype

LV=linetype

[Graphics]
specifies the line type for reference lines requested by the VREF= option. The default is 2, which produces a dashed line.

MU=value

specifies the mean $\mu$ for a normal P-P plot requested with the NORMAL option. For examples, see Figure 8.1, or Figure 8.2 and Figure 8.3. By default, the sample mean is used for $\mu$ .

NAME='string '

[Graphics]
specifies a name for the plot, up to eight characters, that appears in the PROC GREPLAY master menu. The default name is 'CAPABILI'.

NOFRAME

suppresses the frame around the subplot area.

NOLINE

suppresses the diagonal reference line.

NOOBSLEGEND

NOOBSL

[Line Printer]
suppresses the legend that indicates the number of hidden observations.

NORMAL<(normal-options )>

NORM<(normal-options )>

creates a normal P-P plot. By default, if you do not specify a distribution option, the procedure displays a normal P-P plot. To create the plot, the n nonmissing observations are ordered from smallest to largest:

The y-coordinate of the i^th point is the empirical cdf value [i/n]. The x-coordinate is the theoretical normal cdf value


		 
 
where  is the cumulative standard normaldistribution function, and 
 
		  location parameter or mean
		  scale parameter or standard   deviation

You can specify $\mu$ and $\sigma$ with the MU= and SIGMA= normal-options, as illustrated in the following example:

   proc capability data=measures;
      ppplot width / normal(mu=1 sigma=2);
   run;

By default, the sample mean and sample standard deviation are used for $\mu$ and $\sigma$ .

If the data are normally distributed with parameters $\mu$ and $\sigma$ , the points on the plot for MU= $\mu$ and SIGMA= $\sigma$ tend to fall on or near the diagonal line y=x, which is displayed by default. Agreement between the diagonal line and the point pattern is evidence that the specified normal distribution is a good fit. For an example, see Figure 8.1.

PPSYMBOL='character'

[Line Printer]
specifies the character used to plot the points when the P-P plot is produced on a line printer. The default is the plus sign (+).

SCALE=value

is an alias for the SIGMA= option with the BETA, EXPONENTIAL, GAMMA, and WEIBULL options and an alias for the ZETA= option with the LOGNORMAL option. See the entries for the SIGMA= and ZETA= options.

SHAPE=value

is an alias for the ALPHA= option with the GAMMA option, for the SIGMA= option with the LOGNORMAL option, and for the C= option with the WEIBULL option. See the entries for the ALPHA=, C=, and SIGMA= options.

SIGMA=value

specifies the parameter $\sigma$ , where $\sigma\gt$ .When used with the BETA, EXPONENTIAL, GAMMA, NORMAL, and WEIBULL options, the SIGMA= option specifies the scale parameter. When used with the LOGNORMAL option, the SIGMA= option specifies the shape parameter. For an example of the SIGMA= option used with the NORMAL option, see Figure 8.1.

SQUARE

displays the P-P plot in a square frame. The default is a rectangular frame. See Figure 8.1 for an example.

SYMBOL='character'

[Line Printer]
specifies the character used to plot the diagonal reference line for a line printer. The default character is the first letter of the distribution option keyword.

THETA=value

specifies the lower threshold parameter $\theta$ for plots requested with the BETA, EXPONENTIAL, GAMMA, LOGNORMAL, and WEIBULL options.

THRESHOLD=value

is an alias for the THETA= option.

VAXIS=name

[Graphics]
specifies the name of an AXIS statement describing the vertical axis. For an example, see Figure 8.2 and Figure 8.3.

VMINOR=n

VM=n

[Graphics]
specifies the number of minor tick marks between each major tick mark on the vertical axis. Minor tick marks are not labeled. The default is 0.

VREF=value-list

draws reference lines perpendicular to the vertical axis at the values specified. See the entries for the VREFCHAR=, CVREF=, and LVREF= options.

VREFCHAR='character'

[Line Printer]
specifies the character used to form the reference lines requested by the VREF= option for a line printer. The default is the hyphen (-).

VREFLABELS='label1' ... 'labeln'

VREFLABEL='label1' ... 'labeln'

VREFLAB='label1' ... 'labeln'

specifies labels for the reference lines requested by the VREF= option. The number of labels must equal the number of lines. Enclose each label in quotes. Labels can be up to 16 characters.

W=n

[Graphics]
specifies the width in pixels for the diagonal reference line. Specify the W= option in parentheses following a distribution option keyword. For a similar syntax example, see the entry for the L= option. The default is 1.

WEIBULL<(Weibull-options)>

WEIB<(Weibull-options)>

creates a Weibull P-P plot. To create the plot, the n nonmissing observations are ordered from smallest to largest:

The y-coordinate of the i^th point is the empirical cdf value [i/n]. The x-coordinate is the theoretical Weibull cdf value


		 
 
where 
 
		  threshold parameter
		  scale parameter  
		 c = shape parameter (c >0)

You can specify c, $\sigma$ , and $\theta$ with the C=, SIGMA=, and THETA= Weibull-options, as illustrated in the following example:

   proc capability data=measures;
      ppplot width / weibull(theta=1 sigma=2);
   run;

If you do not specify values for these parameters, then by default $\theta=0$ and maximum likelihood estimates are calculated for $\sigma$ and c.

IMPORTANT: Your data must be greater than or equal to the lower threshold $\theta$ . If the default $\theta=0$ is not an adequate lower bound for your data, you should specify $\theta$ with the THETA= option.

If the data are Weibull distributed with parameters c, $\sigma$ , and $\theta$ , the points on the plot for C=c, SIGMA= $\sigma$ , and THETA= $\theta$ tend to fall on or near the diagonal line y=x, which is displayed by default. Agreement between the diagonal line and the point pattern is evidence that the specified Weibull distribution is a good fit. You can specify the SHAPE= option as an alias for the C= option, the SCALE= option as an alias for the SIGMA= option, and the THRESHOLD= option as an alias for the THETA= option.

ZETA=value

specifies a value for the scale parameter $\zeta$ for lognormal P-P plots requested with the LOGNORMAL option.

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