Data Smoothing: Thin-Plate Spline |
The Method Tab
You can use the Method tab (Figure 19.5) to specify options for the thin-plate spline algorithm.
The following options are available:
- Selection method
- specifies how to choose the smoothing penalty parameter. This option corresponds to the SELECT= option in the MODEL statement.
- GCV
- selects the smoothing parameter that minimizes the generalized cross validation criterion.
- Approx. model DF
- selects the smoothing parameter for which the trace of the prediction matrix is closest to the Target model DF. This corresponds to SELECT=DF option.
- Manual
- enables you to specify the value in the log(n*lambda) field. This corresponds to the LOGNLAMBDA= option.
- Maximum number of unique design points
- specifies a limit on the number of unique design points, , in the model. This option corresponds to the DISTANCE= option in the MODEL statement in the following way: the value in this field is used to compute a value for the DISTANCE= option so that there are at most design points. This option is useful for large data sets, since the TPSPLINE procedure is computationally expensive.
Figure 19.5: The Method Tab
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