Model Browser User's Guide

Free Knot Splines

The

basis is not the best suited for the purposes of estimation and evaluation, as the design matrix might be poorly conditioned. In addition, the number of arithmetic operations required to evaluate the spline function depends on the location of relative to the knots. These properties can lead to numeric inaccuracies, especially when the number of knots is large. You can reduce such problems by employing B-splines.

The most important aspect is that for moderate m the design matrix expressed in terms of B-splines is relatively well conditioned.

For this model class, response features can be chosen as

• Fit constants
  
  
• Knot position vector .
• Value of the fit function
  
  at a user specified value
  
  

Truncated Power Series Basis (TPSBS) Splines

Three Parameter Logistic Model