POWERS <data> / POW_VARS=<List_of_variables> DEGREE=<d>
computes all possible products of powers up to degree <d>
of variables in POW_VARS as (new) variables.
Since the number of new variables may be high, the scope of the
data file must often be extended by FILE EXPAND operation before using
POWERS.
Example:
POWERS D2 / POW_VARS=Height(H),Weight(W) DEGREE=3
creates and computes variables H2, H1W1, W2, H3, H2W1, H1W2, W3
where, for example, H2W1 is Height^2*Weight.
The types of new variables are given by TYPE=<1|2|4|8> (default is 8).
The maximum # of power variables is 10 and the maximum degree is 20.
Too long names (over 8 characters) like A1B2C3D4F5 are presented as
X12345. Actual expressions like A^3*B^2*C are given as extensions of
names.
POWERS is a tool for generating variables for polynomial regression
analysis and its generalizations (to be computed by LINREG, for
example).
1 = Transformation of variables in Survo data sets
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