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From | Roger Newson <r.newson@imperial.ac.uk> |
To | "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu> |
Subject | st: New version of -prodvars- on SSC |
Date | Thu, 10 Feb 2011 12:47:07 +0000 |
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. --------------------------------------------------------------------------- package prodvars from http://www.imperial.ac.uk/nhli/r.newson/stata10 --------------------------------------------------------------------------- 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 --------------------------------------------------------------------------- (click here to return to the previous screen) * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/