st: New version of -prodvars- on SSC

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

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

The -prodvars- package is described as below on my website, and is 
expected to be useful in defining design matrices for multivariate 
spline models, or for models combining splines for continuous factors 
with indicator (dummy) variables for discrete factors. The new version 
adds a -generate()- option, allowing the user to specify that the 
generated product variables will be prefixed with a stub and suffixed 
with the sequence number of the generated product variable, ordered 
primarily in the order of the left input varlist and secondarily in the 
order of the right input varlist. (In default, names for the product 
variables are generated from the names of the corresponding input 
variables.) It also adds options -lcharlist()- and -rcharlist()-, 
allowing the output product variables to inherit lists of variable 
characteristics from the corresponding left and right input variables, 
respectively. In addition, it adds an option -ccharlist()-, allowing the 
output product variables to have a list of variable characteristics 
evaluated by combining the variable characteristics of the same names 
for the corresponding left and right input variables, using the new 
options -ccprefix()-, -ccsuffix()- and -ccseparator()- to specify 
prefix, suffix and separator strings, respectively. I have also added a 
-fast- option, allowing the user to choose whether or not -prodvars- 
does extra work to preserve the original dataset (without the added 
product variables( if the user presses -Break-.

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 prodvars from http://www.imperial.ac.uk/nhli/r.newson/stata10
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TITLE
      prodvars: Create product variables for two lists of input variables

DESCRIPTION/AUTHOR(S)
      prodvars inputs 2 variable lists, known as the left variable list and
      the right variable list. It produces as output a list of generated
      variables, one for each pair of variables from the left and right
      variable lists, each with a variable names derived either from a stub
      or from the names of the pair of input variables, and values equal to
      the products of the values of the two input variables. Optionally,
      the generated variables may also have variable labels derived from
      the variable labels, or variable names, of the input variables.
      prodvars is useful for calculating variables for the design matrix
      of a multiple-intercept model.

      Author: Roger Newson
      Date: 08 February 2011
      Stata version: 10

INSTALLATION FILES                                  (click here to install)
      prodvars.ado
      prodvars.sthlp
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