## Avoiding Constant Transformations

There are times when the optimal scaling produces a constant transformed
variable. This can happen with the MONOTONE, UNTIE, and MSPLINE
transformations when the target is negatively correlated with the
original input variable. It can happen with all transformations when
the target is uncorrelated with the original input variable. When this
happens, the procedure modifies the target to avoid a constant
transformation. This strategy avoids certain nonoptimal solutions.
If the transformation is monotonic and a constant transformed variable
results, the procedure multiplies the target by -1 and tries the
optimal scaling again. If the transformation is not monotonic or if the
multiplication by -1 did not help, the procedure tries using a random
target. If the transformation is still constant, the previous
nonconstant transformation is retained. When a constant transformation
is avoided by any strategy, this message is displayed:
"A constant transformation was avoided for *name*."

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