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st: New package -polyspline- on SSC


From   "Roger B. Newson" <r.newson@imperial.ac.uk>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   st: New package -polyspline- on SSC
Date   Tue, 31 Dec 2013 17:06:27 +0000

Thanks once again to Kit Baum, a new package -polyspline- is now available for download from SSC. In Stata, use the -ssc- command to do this.

The -polyspline- packge is described as below on my website, and is an easy-to-use front-end for the existing SSC package -bspline-. It inputs an X-variable and a list of reference points on the X-axis, and generates a list of reference splines, one per reference point. These reference splines can be included in the list of covariates for a regresssion model, and the corresponding parameters will then be values of the spline model at the reference points, or differences between those reference values. In default, the degree of the spline model is one less than the number of reference points, implying that the spline is simply a polynomial, with no internal knots. If the user specifies lower degree spline using the -power()- option, then the internal knots will automatically be interpolate between the reference points, in such a way as to guarantee that the reference splines will exist.

Best wishes

Roger

--
Roger B Newson BSc MSc DPhil
Lecturer in Medical Statistics
Respiratory Epidemiology, Occupational Medicine
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.

---------------------------------------------------------------------------
package polyspline from http://www.imperial.ac.uk/nhli/r.newson/stata10
---------------------------------------------------------------------------

TITLE
      polyspline: Generate sensible bases for polynomials and other splines

DESCRIPTION/AUTHOR(S)
      The polyspline package inputs an X-variable and a list of
      reference points on the X-axis, and generates a basis of
      reference splines (one per reference point) for a polynomial
      or other unrestricted spline.  This basis can be included in
      the list of covariates of a regression model.  The estimated
      parameters will then be values of the spline at the reference
      points, or differences between values of the spline at the
      reference points and the value of the spline at a base
      reference point.  polyspline is an easy-to-use front end for
      the SSC package bspline, which must be installed for
      polyspline to work.

      Author: Roger Newson
      Distribution-date: 25 December 2013
      Stata-version: 10


INSTALLATION FILES                                  (click here to install)
      polyspline.ado
      polyspline.sthlp
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(click here to return to the previous screen)
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