st: New version of -bspline- on SSC

[Roger Newson <r.newson@imperial.ac.uk>]

Thanks to Kit Baum as always, a new version of the -bspline- package is 
now available for download from SSC. In Stata, use the -ssc- package to 
do this, or -adoupdate- if you already have an old version of -bspline-.

The -bspline- package is described as below on my website. The new 
version adds a new option -krule()- to the -flexcurv- module. -flexcurv- 
is designed as an easy-to-use program for computing a basis of 
unrestricted reference splines, whose corresponding parameters (when 
included in the design matrix of a regression model) are values of the 
spline at reference points on the X-axis, or differences between the 
values of the spline at these reference points and values of the spline 
at a base reference point. (Therefore, the reference splines do the job, 
for continuous factors, that dummy variables do for discrete factors.) 
The -krule()- option specifies the knot rule, used by -flexcurv- to 
generate the list of knots for the splines. It can be -krule(regular)- 
(the default), specifying regularly-spaced knots. Or it can be 
-krule(interpolate)-, specifying that the knots will be interpolated 
between the reference points in such a way as to guarantee that a basis 
of reference splines will exist, whether or not the reference points 
themselves are regularly spaced. If the reference points are regularly 
spaced, then -krule(regular)- and -krule(interpolate)- should produce 
the same sequence of knots.

Best wishes

Roger


--
Roger B Newson BSc MSc DPhil
Lecturer in Medical Statistics
Respiratory Epidemiology and Public Health Group
National Heart and Lung Institute
Imperial College London
Royal Brompton Campus
Room 33, Emmanuel Kaye Building
1B Manresa Road
London SW3 6LR
UNITED KINGDOM
Tel: +44 (0)20 7352 8121 ext 3381
Fax: +44 (0)20 7351 8322
Email: r.newson@imperial.ac.uk
Web page: http://www.imperial.ac.uk/nhli/r.newson/
Departmental Web page:
http://www1.imperial.ac.uk/medicine/about/divisions/nhli/respiration/popgenetics/reph/

Opinions expressed are those of the author, not of the institution.

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package bspline from http://www.imperial.ac.uk/nhli/r.newson/stata10
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TITLE
      bspline: Create a basis of B-splines or reference splines

DESCRIPTION/AUTHOR(S)
      The bspline package contains 3 commands, bspline, frencurv
      and flexcurv.  bspline generates a basis of B-splines in the
      X-variate based on a list of knots, for use in the design
      matrix of a regression model.  frencurv generates a basis of
      reference splines, for use in the design matrix of a
      regression model, with the property that the parameters
      fitted will be values of the spline at a list of reference
      points.  flexcurv is an easy-to-use version of frencurv, and
      generates reference splines with regularly-spaced knots, or
      with knots interpolated between the reference points.
      frencurv and flexcurv have the additional option of
      generating an incomplete basis of reference splines, which
      can be completed by the addition of the standard constant
      variable used in regression models.  The splines are either
      given the names in the newvarlist (if present), or (more
      usually) generated as a list of numbered variables, prefixed
      by the generate() option.  Usually (but not always), the
      regression command is called using the noconst option.

      Author: Roger Newson
      Distribution-date: 02 March 2011
      Stata-version: 10


INSTALLATION FILES                                  (click here to install)
      bspline.ado
      bspline.sthlp
      frencurv.ado
      frencurv.sthlp
      flexcurv.ado
      flexcurv.sthlp

ANCILLARY FILES                                     (click here to get)
      bspline.pdf
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