The DTREE Procedure |
The MODIFY statement is used to change either the type of a stage or
the reward from an outcome. If MODIFY outcome-name REWARD
new-value is given where the outcome-name is
an outcome specified in the
STAGEIN= data set, and new-value
is a numeric value, then
the reward of the outcome named
outcome-name is changed to new-value.
If MODIFY stage-name TYPE is given where stage-name is a
stage name specified in the STAGEIN= data set,
then the type of the stage
named stage-name is changed to 'DECISION'
if its current type
is 'CHANCE'
and is changed to 'CHANCE'
if its current type
is 'DECISION'
. You cannot
change the type of an 'END'
stage. The change of the type of
a stage from 'CHANCE'
to 'DECISION'
can help
the decision-maker learn how much improvement
can be expected if he or she could pick which of the future (or unknown)
outcomes would occur.
However, if you want to change the type of
a stage from 'DECISION'
to 'CHANCE'
, the procedure
is not able to
determine the probabilities for its outcomes unless you specify them
in the PROBIN= data set.
Copyright © 2008 by SAS Institute Inc., Cary, NC, USA. All rights reserved.