The PRINQUAL Procedure
- Overview
- Getting Started
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Syntax
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Details
The Three Methods of Variable Transformation Understanding How PROC PRINQUAL Works Splines Missing Values Controlling the Number of Iterations Performing a Principal Component Analysis of Transformed Data Using the MAC Method Output Data Set Avoiding Constant Transformations Constant Variables Character OPSCORE Variables REITERATE Option Usage Passive Observations Computational Resources Displayed Output ODS Table Names ODS Graphics
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Examples
- References
| 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."