st: New versions of -xcollapse- and -xcontract- on SSC

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

Thanks as always to the greatly appreciated services of Kit Baum, new 
versions of the -xcollapse- and -xcontract- packages are now available 
for download from SSC. In Stata, use the -ssc- command to do this, or 
-adoupdate- if you already have old versions of -xcollapse- and -xcontract-.

The -xcollapse- and -xcontract- packages are described as below on my 
website, and are extended versions of -collapse- and -contract-, 
respectively. The new versions fix a bug, which caused problems for 
users of some updates of Stata Version 10, in which the -index()- 
function became temporarily unavailable because it had been superseded 
by -strpos()-. The -index()- function was quietly restored by StataCorp 
in a later update, following protests from users on Statalist (which 
StataCorp listened to as they always do). However, some Stata 10 users 
out there still have the updates in which -index()- was missing, so I 
have replaced all calls to -index()- in both packages with calls to 
-strpos()-, so the packages should now work, even for those users.

I would like to thank my former colleague Ramyani Gupta, now at St 
George's University in London, UK, for alerting me to this outstanding 
problem.

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

TITLE
      xcollapse: Make data set of summary statistics on disk or in memory

DESCRIPTION/AUTHOR(S)
      xcollapse is an extended version of collapse, which creates a 
data set with
      one observation per combination of values of a list of variables 
in the
      existing data set and new variables containing summary statistics 
of other
      variables (eg means) in each combination. xcollapse allows the 
user to choose
      the destination of the output data set, which may either be 
listed to the
      Stata log, or saved to a disk file, or written to the memory 
(overwriting any
      existing data set).

      Author: Roger Newson
      Distribution-Date: 27september2011
      Stata-Version: 10

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

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

TITLE
      xcontract: Make dataset of frequencies and percents on disk or in 
memory

DESCRIPTION/AUTHOR(S)
      xcontract is an extended version of contract. It creates a data 
set with one
      observation per combination of values of a list of variables in 
the existing
      data set and new variables containing the frequency and percent 
of each
      combination, and, optionally, the cumulative frequency and 
percent of each
      combination. A list of by-variables can be used with xcontract, 
and the
      percents will then be calculated within by-groups. The output 
data set may
      either be listed to the Stata log, or saved to a disk file, or 
written to the
      memory (overwriting any existing data set).

      Author: Roger Newson
      Distribution-Date: 29september2011
      Stata-Version: 10

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