inflogis Influence plot for logistic regression models inflogis

Visualizing Categorical Data: inflogis

$Version: 1.3 (24 May 2000)
Michael Friendly
York University

The inflogis macro ( [download] get inflogis.sas)

Influence plot for logistic regression models

The INFLOGIS macro produces influence plots for a logistic regression model. The plot shows a measure of badness of fit for a given case (DIFDEV or DIFCHISQ) vs. the fitted probability (PRED) or leverage (HAT), using an influence measure (C or CBAR) as the size of a bubble symbol.

Usage

The INFLOGIS macro is called with keyword parameters. The arguments may be listed within parentheses in any order, separated by commas. For example: 
%inflogis(data=icu, y=died, x=age  cancer  uncons admit, id=id, gx=hat);

Parameters

DATA=
Specifies the name of the input data set to be analyzed. [Default: DATA=_LAST_]
Y=
Name of the response variable
TRIALS=
Name of trials variable (for event/trials syntax)
X=
Names of predictors
ID=
Name of observation ID variable (char)
OUT=
Name of the output data set [Default: OUT=_DIAG_]
GY=
Ordinate for plot: DIFDEV or DIFCHISQ [Default: GY=DIFDEV]
GX=
Abscissa for plot: PRED or HAT [Default: GX=PRED]
BUBBLE=
Bubble proportional to: C or CBAR [Default: BUBBLE=C]
LABEL=
Points to label: ALL, NONE, or INFL [Default: LABEL=INFL]
DEV=
DIFDEV/DIFCHISQ criterion for influential points [Default: DEV=4]
LSIZE=
Observation label size. The height of other text is controlled by the HTEXT= goption. [Default: LSIZE=1.5]
LCOLOR=
Observation label color [Default: LCOLOR=BLACK]
LPOS=
Observation label position [Default: LPOS=5]
BSIZE=
Bubble size scale factor [Default: BSIZE=10]
BSCALE=
Bubble size proportional to AREA or RADIUS [Default: BSCALE=AREA]
BCOLOR=
Bubble color [Default: BCOLOR=BLACK]
REFCOL=
Color of reference lines [Default: REFCOL=BLACK]
REFLIN=
Line style for reference lines; 0->NONE [Default: REFLIN=33]
LOPTIONS=
Options for PROC LOGISTIC [Default: LOPTIONS=NOPRINT]
NAME=
Name of the graph in the graphic catalog [Default: NAME=INFLOGIS]
GOUT=
Name of the graphics catalog

Example

Plot change in deviance (DIFDEV) against hat value (HAT) for the ICU data: 
%include vcd(inflogis);        *-- or include in an autocall library;
%include data(icu);

%inflogis(data=icu, y=died, x=age  cancer  uncons admit, id=id, gx=hat);

See also

inflglim Influence plots for generalized linear models
inflplot Influence plot for regression models
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