PREDPPLOT Statement |
The PREDPPLOT statement plots the predicted probability against a single continuous variable (dose variable) in the MODEL statement for both the binomial model and the multinomial model. Confidence limits are available only for the binomial model. An attached box on the right side of the plot is used to label predicted probability curves with the names of their levels for the multinomial model. You can specify the color of this box by using the CLABBOX= option.
specifies a single continuous variable (dose variable) in the independent variable list of the MODEL statement. If a VAR= variable is not specified, the first single continuous variable in the independent variable list of the MODEL statement is used. If such a variable does not exist in the independent variable list of the MODEL statement, an error is reported.
The predicted probability is
for the binomial model and
for the multinomial model with response levels, where is the cumulative distribution function used to model the probability, is the vector of the covariates, are the estimated ordinal intercepts with , is the threshold parameter, either known or estimated from the model, and is the vector of estimated parameters.
To plot (or ) as a function of a continuous variable , the remaining covariates must be specified. You can use the XDATA= option to provide the values of (see the XDATA= option in the PROC PROBIT statement for details), or use the default values that follow these rules:
If the effect contains a continuous variable (or variables), the overall mean of this effect is used.
If the effect is a single classification variable, the highest level of the variable is used.
enable you to plot the observed data and add features to the plot.
You can use options in the PREDPPLOT statement to do the following:
superimpose specification limits
suppress or add observed data points for the binomial model
suppress or add confidence limits for the binomial model
specify the levels for which predicted probability curves are requested for the multinomial model
specify graphical enhancements (such as color or text height)
Table 74.26 through Table 74.32 list all options by function. The Dictionary of Options describes each option in detail.
LEVEL=(character-list) |
Specifies the names of the levels for which the predicted probability curves are requested (only for the multinomial model) |
NOCONF |
Suppresses confidence limits |
NODATA |
Suppresses observed data points on the plot |
NOTHRESH |
Suppresses the threshold line |
THRESHLABPOS=value |
Specifies the position for the label of the threshold line |
CAXIS=color |
Specifies color for the axes |
CFIT=color |
Specifies color for fitted curves |
CFRAME=color |
Specifies color for frame |
CGRID=color |
Specifies color for grid lines |
CHREF=color |
Specifies color for HREF= lines |
CLABBOX=color |
Specifies color for label box |
CTEXT=color |
Specifies color for text |
CVREF=color |
Specifies color for VREF= lines |
ANNOTATE=SAS-data-set |
Specifies an Annotate data set |
INBORDER |
Requests a border around plot |
LFIT=linetype |
Specifies line style for fitted curves and confidence limits |
LGRID=linetype |
Specifies line style for grid lines |
NOFRAME |
Suppresses the frame around plotting areas |
NOGRID |
Suppresses grid lines |
NOFIT |
Suppresses fitted curves |
NOHLABEL |
Suppresses horizontal labels |
NOHTICK |
Suppresses horizontal ticks |
NOVTICK |
Suppresses vertical ticks |
TURNVLABELS |
Vertically strings out characters in vertical labels |
WFIT=n |
Specifies thickness for fitted curves |
WGRID=n |
Specifies thickness for grids |
WREFL=n |
Specifies thickness for reference lines |
HAXIS=value1 to value2 <by value3> |
Specifies tick mark values for horizontal axis |
HOFFSET=value |
Specifies offset for horizontal axis |
HLOWER=value |
Specifies lower limit on horizontal axis scale |
HUPPER=value |
Specifies upper limit on horizontal axis scale |
NHTICK=n |
Specifies number of ticks for horizontal axis |
NVTICK=n |
Specifies number of ticks for vertical axis |
VAXIS=value1 to value2 <by value3> |
Specifies tick mark values for vertical axis |
VAXISLABEL=’label’ |
Specifies label for vertical axis |
VOFFSET=value |
Specifies offset for vertical axis |
VLOWER=value |
Specifies lower limit on vertical axis scale |
VUPPER=value |
Specifies upper limit on vertical axis scale |
WAXIS=n |
Specifies thickness for axis |
DESCRIPTION=’string’ |
Specifies description for graphics catalog member |
NAME=’string’ |
Specifies name for plot in graphics catalog |
FONT=font |
Specifies software font for text |
HEIGHT=value |
Specifies height of text used outside framed areas |
INFONT=font |
Specifies software font for text inside framed areas |
INHEIGHT=value |
Specifies height of text inside framed areas |
HREF<(INTERSECT)>=value-list |
Requests horizontal reference line |
HREFLABELS=(’label1’,...,’labeln’) |
Specifies labels for HREF= lines |
HREFLABPOS=n |
Specifies vertical position of labels for HREF= lines |
LHREF=linetype |
Specifies line style for HREF= lines |
LVREF=linetype |
Specifies line style for VREF= lines |
VREF<(INTERSECT)>=value-list |
Requests vertical reference line |
VREFLABELS=(’label1’,...,’labeln’) |
Specifies labels for VREF= lines |
VREFLABPOS= |
Specifies horizontal position of labels for VREF= lines |
The following entries provide detailed descriptions of the options in the PREDPPLOT statement.
specifies an Annotate data set, as described in SAS/GRAPH Software: Reference, that enables you to add features to the predicted probability plot. The ANNOTATE= data set you specify in the PREDPPLOT statement is used for all plots created by the statement.
specifies the color used for the axes and tick marks. This option overrides any COLOR= specifications in an AXIS statement. The default is the first color in the device color list.
specifies the color for the fitted predicted probability curves. The default is the first color in the device color list.
specifies the color for the area enclosed by the axes and frame. This area is not shaded by default.
specifies the color for grid lines. The default is the first color in the device color list.
specifies the color for lines requested by the HREF= option. The default is the first color in the device color list.
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.
specifies the color for lines requested by the VREF= option. The default is the first color in the device color list.
specifies a description, up to 40 characters, that appears in the PROC GREPLAY master menu. The default is the variable name.
specifies a software font for reference line and axis labels. You can also specify fonts for axis labels in an AXIS statement. The FONT= font takes precedence over the FTEXT= font specified in the most recent GOPTIONS statement. Hardware characters are used by default.
specifies tick mark values for the horizontal axis; value1, value2, and value3 must be numeric, and value1 must be less than value2. The lower tick mark is value1. Tick marks are drawn at increments of value3. The last tick mark is the greatest value that does not exceed value2. If value3 is omitted, a value of 1 is used.
Examples of HAXIS= lists follow:
haxis = 0 to 10 haxis = 2 to 10 by 2 haxis = 0 to 200 by 10
specifies the lower limit on the horizontal axis scale. The HLOWER= option specifies value as the lower horizontal axis tick mark. The tick mark interval and the upper axis limit are determined automatically. This option has no effect if the HAXIS= option is used.
specifies the offset for the horizontal axis. The default value is 1.
specifies value as the upper horizontal axis tick mark. The tick mark interval and the lower axis limit are determined automatically. This option has no effect if the HAXIS= option is used.
requests reference lines perpendicular to the horizontal axis. If (INTERSECT) is specified, a second reference line perpendicular to the vertical axis is drawn that intersects the fit line at the same point as the horizontal axis reference line. If a horizontal axis reference line label is specified, the intersecting vertical axis reference line is labeled with the vertical axis value. See also the CHREF=, HREFLABELS=, and LHREF= options.
specifies labels for the 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.
specifies the vertical position of labels for HREF= lines. The following table shows valid values for n and the corresponding label placements.
n |
label placement |
1 |
Top |
2 |
Staggered from top |
3 |
Bottom |
4 |
Staggered from bottom |
5 |
Alternating from top |
6 |
Alternating from bottom |
specifies the names of the levels for which predicted probability curves are requested. Names should be quoted and separated by space. If there is no correct name provided, no fitted probability curve is plotted.
specifies a line style for fitted curves and confidence limits. By default, fitted curves are drawn by connecting solid lines (linetype = 1) and confidence limits are drawn by connecting dashed lines (linetype = 3).
specifies a line style for all grid lines. The value for linetype is between 1 and 46. The default is 35.
specifies the line type for lines requested by the HREF= option. The default is 2, which produces a dashed line.
specifies the line type for lines requested by the VREF= option. The default is 2, which produces a dashed line.
specifies a name for the plot, up to eight characters, that appears in the PROC GREPLAY master menu. The default is ’PROBIT’.
suppresses confidence limits from the plot. This works only for the binomial model. Confidence limits are not plotted for the multinomial model.
suppresses observed data points from the plot. This works only for the binomial model. The data points are not plotted for the multinomial model.
specifies the horizontal position of labels for the threshold line. The following table shows valid values for n and the corresponding label placements.
n |
label placement |
1 |
Left |
2 |
Right |
specifies tick mark values for the vertical axis; value1, value2, and value3 must be numeric, and value1 must be less than value2. The lower tick mark is value1. Tick marks are drawn at increments of value3. The last tick mark is the greatest value that does not exceed value2. This method of specification of tick marks is not valid for logarithmic axes. If value3 is omitted, a value of 1 is used.
Examples of VAXIS= lists follow:
vaxis = 0 to 10 vaxis = 0 to 2 by .1
specifies the lower limit on the vertical axis scale. The VLOWER= option specifies value as the lower vertical axis tick mark. The tick mark interval and the upper axis limit are determined automatically. This option has no effect if the VAXIS= option is used.
requests reference lines perpendicular to the vertical axis. If (INTERSECT) is specified, a second reference line perpendicular to the horizontal axis is drawn that intersects the fit line at the same point as the vertical axis reference line. If a vertical axis reference line label is specified, the intersecting horizontal axis reference line is labeled with the horizontal axis value. See also the CVREF=, LVREF=, and VREFLABELS= options.
specifies labels for the 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.
specifies the horizontal position of labels for VREF= lines. The following table shows valid values for n and the corresponding label placements.
n |
label placement |
1 |
Left |
2 |
Right |
specifies the upper limit on the vertical axis scale. The VUPPER= option specifies value as the upper vertical axis tick mark. The tick mark interval and the lower axis limit are determined automatically. This option has no effect if the VAXIS= option is used.
specifies line thickness for axes and frame. The default value is 1.
specifies line thickness for fitted curves. The default value is 1.
specifies line thickness for reference lines. The default value is 1.