PLOT
<yvariable*xvariable> <=symbol> <…yvariable*xvariable> <=symbol> </ options> ;
The PLOT statement is used with line printer and traditional graphics. See the PLOTS= option for information about using ODS graphics to create modern statistical graphics.
The PLOT statement in PROC REG displays scatter plots with yvariable on the vertical axis and xvariable on the horizontal axis. Line printer plots are generated if the LINEPRINTER option is specified in the PROC REG statement; otherwise, the traditional graphics are created. Points in line printer plots can be marked with symbols, while global graphics statements such as GOPTIONS and SYMBOL are used to enhance the traditional graphics. Note that the plots you request by using the PLOT statement are independent of the ODS graphical displays (see the section ODS Graphics) that are available in PROC REG.
As with most other interactive statements, the PLOT statement implicitly refits the model. For example, if a PLOT statement is preceded by a REWEIGHT statement, the model is recomputed, and the plot reflects the new model.
If there are multiple MODEL statements preceding a PLOT statement, then the PLOT statement refers to the latest MODEL statement.
The PLOT statement cannot be used when a TYPE=CORR, TYPE=COV, or TYPE=SSCP data set is used as input to PROC REG.
You can specify several PLOT statements for each MODEL statement, and you can specify more than one plot in each PLOT statement.
More than one yvariable*xvariable pair can be specified to request multiple plots. The yvariables and xvariables can be as follows:
any variables specified in the VAR or MODEL statement before the first RUN statement
keyword., where keyword is a regression diagnostic statistic available in the OUTPUT statement (see Table 79.7). For example,
plot predicted.*residual.;
generates one plot of the predicted values by the residuals for each dependent variable in the MODEL statement. These statistics can also be plotted against any of the variables in the VAR or MODEL statements.
the keyword OBS. (the observation number), which can be plotted against any of the preceding variables
the keyword NPP. or NQQ., which can be used with any of the preceding variables to construct normal PP or QQ plots, respectively (see the section Construction of QQ and PP Plots for more information)
keywords for model fit summary statistics available in the OUTEST= data set with _TYPE_
= PARMS (see Table 79.7). A SELECTION= method (other than NONE) must be requested in the MODEL statement for these variables to be plotted. If one member of a yvariable*xvariable pair is from the OUTEST= data set, the other member must also be from the OUTEST= data set.
The OUTPUT statement and the OUTEST= option are not required when their keywords are specified in the PLOT statement.
The yvariable and xvariable specifications can be replaced by a set of variables and statistics enclosed in parentheses. When this occurs, all possible combinations of yvariable and xvariable are generated. For example, the following two statements are equivalent:
plot (y1 y2)*(x1 x2); plot y1*x1 y1*x2 y2*x1 y2*x2;
The statement
plot;
is equivalent to respecifying the most recent PLOT statement without any options. However, the line printer options COLLECT, HPLOTS=, SYMBOL=, and VPLOTS=, described in the section Line Printer Plots, apply across PLOT statements and remain in effect if they have been previously specified.
Options used for the traditional graphics are described in the following section; see Line Printer Plots for more information.
The display of traditional graphics is described in the following paragraphs, the options are summarized in Table 79.7 and described in the section “Dictionary of PLOT Statement Options”.
Several line printer statements and options are not supported for the traditional graphics. In particular the PAINT statement is disabled, as are the PLOT statement options CLEAR, COLLECT, HPLOTS=, NOCOLLECT, SYMBOL=, and VPLOTS=. To display more than one plot per page or to collect plots from multiple PLOT statements, use the PROC GREPLAY statement (see SAS/GRAPH: Reference). Also note that traditional graphics options are not recognized for line printer plots.
The fitted model equation and a label are displayed in the top margin of the plot; this display can be suppressed with the NOMODEL option. If the label is requested but cannot fit on one line, it is not displayed. The equation and label are displayed on one line when possible; if more lines are required, the label is displayed in the first line with the model equation in successive lines. If displaying the entire equation causes the plot to be unacceptably small, the equation is truncated. Table 79.8 lists options to control the display of the equation.
Four statistics are displayed by default in the right margin: the number of observations, R square, the adjusted R square, and the root mean square error. The display of these statistics can be suppressed with the NOSTAT option. You can specify other options to request the display of various statistics in the right margin; see Table 79.8.
A default reference line at zero is displayed if residuals are plotted. If the dependent variable is plotted against the independent variable in a simple linear regression model, the fitted regression line is displayed by default. Default reference lines can be suppressed with the NOLINE option; the lines are not displayed if the OVERLAY option is specified.
Specialized plots are requested with special options. For each coefficient, the RIDGEPLOT option plots the ridge estimates against the ridge values k; see the description of the RIDGEPLOT option in the section “Dictionary of PLOT Statement Options” for more details. The CONF option plots % confidence intervals for the mean while the PRED option plots % prediction intervals; see the description of these options in the section “Dictionary of PLOT Statement Options” for more details.
If a SELECTION= method is requested, the fitted model equation and the statistics displayed in the margin correspond to the selected model. For the ADJRSQ and CP methods, the selected model is treated as a submodel of the full model. If a CP.*NP. plot is requested, the CHOCKING= and CMALLOWS= options display model selection reference lines; see the descriptions of these options in the section “Dictionary of PLOT Statement Options” for more details.
The following table lists the keywords available as PLOT statement xvariables and yvariables. All keywords have a trailing dot; for example, “COOKD.” requests Cook’s D statistic. Neither the OUTPUT statement nor the OUTEST= option needs to be specified.
Table 79.7: Keywords for PLOT Statement xvariables
Keyword 
Description 

Diagnostic Statistics 

COOKD. 
Cook’s D influence statistics 
COVRATIO. 
standard influence of observation on covariance of betas 
DFFITS. 
standard influence of observation on predicted value 
H. 
leverage 
LCL. 
lower bound of % confidence interval for individual 
LCLM. 
lower bound of % confidence interval for the mean of 
PREDICTED. 
predicted values 
PRESS. 
residuals from refitting the model with current observation deleted 
RESIDUAL.  R. 
residuals 
RSTUDENT. 
studentized residuals with the current observation deleted 
STDI. 
standard error of the individual predicted value 
STDP. 
standard error of the mean predicted value 
STDR. 
standard error of the residual 
STUDENT. 
residuals divided by their standard errors 
UCL. 
upper bound of % confidence interval for individual 
UCLM. 
upper bound of % confidence interval for the mean of 
Other Keywords Used with Diagnostic Statistics 

NPP. 
normal probabilityprobability plot 
NQQ. 
normal quantilequantile plot 
OBS. 
observation number (cannot plot against OUTEST= statistics) 
Model Fit Summary Statistics 

ADJRSQ. 
adjusted Rsquare 
AIC. 
Akaike’s information criterion 
BIC. 
Sawa’s Bayesian information criterion 
CP. 
Mallows’ statistic 
EDF. 
error degrees of freedom 
GMSEP. 
estimated MSE of prediction, assuming multivariate normality 
IN. 
number of regressors in the model not including the intercept 
JP. 
final prediction error 
MSE. 
mean squared error 
NP. 
number of parameters in the model (including the intercept) 
PC. 
Amemiya’s prediction criterion 
RMSE. 
root MSE 
RSQ. 
Rsquare 
SBC. 
SBC statistic 
SP. 
SP statistic 
SSE. 
error sum of squares 
Table 79.8 summarizes the options available in the PLOT statement. These options are available unless the LINEPRINTER option is specified in the PROC REG statement. For complete descriptions, see the section “Dictionary of PLOT Statement Options”.
Table 79.8: Traditional Graphics Options
Option 
Description 

General Graphics Options 

Specifies the annotate data set 

Requests a reference line for model selection criteria 

Requests a reference line for the model selection criterion 

Requests plots of % confidence intervals for the mean 

Specifies a description for graphics catalog member 

Names the plot in the graphics catalog 

Overlays plots from the same model 

Requests plots of % prediction intervals for individual 

Requests the ridge trace for ridge regression 

Axis and Legend Options 

Specifies LEGEND statement to be used 

Suppresses display of the legend 

Specifies tick mark values for horizontal axis 

Specifies tick mark values for vertical axis 

Reference Line Options 

Specifies reference lines perpendicular to horizontal axis 

Specifies line style for HREF= lines 

Specifies line style for lines displayed by default 

Specifies line style for VREF= lines 

Suppresses display of any default reference line 

Specifies reference lines perpendicular to vertical axis 

Color Options 

Specifies color for axis line and tick marks 

Specifies color for frame 

Specifies color for HREF= lines 

Specifies color for lines displayed by default 

Specifies color for text 

Specifies color for VREF= lines 

Options for Displaying the Fitted Model Equation 

Specifies font of model equation and model label 

Specifies text height of model equation and model label 

Specifies model label 

Suppresses display of the fitted model and the label 

Options for Displaying Statistics in the Plot Margin 

Displays Akaike’s information criterion 

Displays Sawa’s Bayesian information criterion 

Displays Mallows’ statistic 

Displays the error degrees of freedom 

Displays the estimated MSE of prediction assuming 

Displays the number of regressors in the model not including 

Displays the statistic 

Displays the mean squared error 

Suppresses display of the default statistics: the number of 

Displays the number of parameters in the model including the 

Displays the PC statistic 

Displays the SBC statistic 

Displays the statistic 

Displays the error sum of squares 

Specifies font of text displayed in the margin 

Specifies height of text displayed in the margin 
The following entries describe the PLOT statement options in detail. Note that these options are available unless you specify the LINEPRINTER option in the PROC REG statement.
Line printer plots are requested with the LINEPRINTER option in the PROC REG statement. Points in line printer plots can be marked with symbols, which can be specified as a single character enclosed in quotes or the name of any variable in the input data set.
If a character variable is used for the symbol, the first (leftmost) nonblank character in the formatted value of the variable is used as the plotting symbol. If a character in quotes is specified, that character becomes the plotting symbol. If a character is used as the plotting symbol, and if there are different plotting symbols needed at the same point, the symbol ’?’ is used at that point.
If an unformatted numeric variable is used for the symbol, the symbols ’1’, ’2’, …, ’9’ are used for variable values 1, 2, …, 9. For noninteger values, only the integer portion is used as the plotting symbol. For values of 10 or greater, the symbol ’*’ is used. For negative values, a ’?’ is used. If a numeric variable is used, and if there is more than one plotting symbol needed at the same point, the sum of the variable values is used at that point. If the sum exceeds 9, the symbol ’*’ is used.
If a symbol is not specified, the number of replicates at the point is displayed. The symbol ’*’ is used if there are 10 or more replicates.
If the LINEPRINTER option is used, you can specify the following options in the PLOT statement after a slash (/):