contour |
contour - IML macro to plot elliptical contours for X, Y data |
contour |

# SAS Macro Programs: `contour`

$Version: 2.4 (10 Oct 2006)

**
Michael Friendly **

York University

The CONTOUR macro plots a bivariate scatterplot with a bivariate
data ellipse for one or more groups. This macro has now been superceded
by the ELLIPSES macro.
### Parameters

- DATA=_LAST_
- Name of the input data set
- X=
- Name of the X variable
- Y=
- Name of the Y variable
- GROUP=
- Group variable. If a GROUP= variable is
specified, one ellipse is produced for each
value of this variable in the data set. If no
GROUP= variable is specified, a single ellipse
is drawn for the entire sample. The GROUP=
variable may be character or numeric.
- PVALUE=.5
- Confidence coefficient(s)
* ( 1 - alpha )
*. This is the proportion of data from a
bivariate normal distribution contained within
the ellipse. Several values may be specified
in a list (e.g., PVALUE=.5 .9), in which case
one ellipse is generated for each value.
- STD=STDERR
- Error bar metric. STD=STDERR gives error
bars equal to each mean
* +- * one
standard error (* s / sqrt n *) for both
variables. STD=STD gives error bars whose
length is one standard deviation for both
variables.
- POINTS=40
- The number of points on each contour.
- ALL=NO
- Specifies whether the contour for the total
sample should be drawn in addition to those for
each group. If there is no GROUP= variable,
ALL=YES just draws the ellipse twice.
- OUT=CONTOUR
- Name of the output Annotate data set used
to draw the ellipses, error bars and group
labels.
- PLOT=YES
- If YES, the macro plots the data together
with the generated ellipses. Otherwise, only
the output Annotate data set is generated.
- I=NONE
- SYMBOL statement interpolate option for
drawing points. Use I=RL to include the
regression line as well.
- NAME=CONTOUR
- The name assigned to the graph(s) in the
graphic catalog.
- COLORS=RED GREEN BLUE BLACK PURPLE YELLOW BROWN ORANGE
- List of colors to use for each of the
groups. If there are
* g * groups,
specify * g * colors if ALL=NO, and * g
+ 1 * colors if ALL=YES. COLORS(i) is used
for group i.
- SYMBOLS=+ SQUARE STAR - PLUS : $ =
- List of symbols, separated by spaces, to
use for plotting points in each of the groups.
SYMBOLS(i) is used for group i.

### Missing data

Observations with missing values on either the X or Y variable are
not plotted and do not enter the computations of the data ellipse.
### Usage Notes

When using the CONTOUR macro with the SAS System for Personal
Computers, it may be neccessary to add the option WORKSIZE=100 to
the PROC IML statement.
When displaying output from the macro on a terminal, it may be
necessary to specify CBACK=WHITE in a GOPTIONS statement.

### Example

%include data(auto) ;
%contour(data=auto,
x=price, y=weight, group=origin,
pvalue=.5);