st: New SSC module: -revrs- to reverse order and keep labels

[Kyle C Longest <klongest@email.unc.edu>]

Thanks to Kit Baum, a new program, -revrs-, is available on SSC.

. ssc install revrs

-revrs- is a module to reverse the order of a variable's values and 
maintain specified value labels. �revrs- is especially helpful for 
quickly recoding multiple categorical or ordinal response variables to 
follow a similar direction.

Version 8.2 of Stata required.

The primary purpose of the program is to allow users to reverse order 
variables in one step, and keep the value labels. This is helpful in 
cases when surveys will ask similar questions but switch the direction 
of the response categories (e.g., is �Never� coded as 0 or as 5). 
Granted most Stata programs will inherently control for this reverse 
ordering, but this program can be helpful for aesthetic (e.g., 
frequency distributions, cross tabs) purposes (especially if the user 
is directly copying tables out of Stata) and to reduce possible 
confusion (e.g., interpreting negative coefficients).

Example:

. tab drink

            drink |      Freq.     Percent        Cum.
-------------------+-----------------------------------
        Every_Day |         99        9.90        9.90
 Almost_Every_Day |        101       10.10       20.00
      Once a Week |         40        4.00       24.00
     Once A month |        159       15.90       39.90
A few times a Year |        301       30.10       70.00
            Never |        300       30.00      100.00
-------------------+-----------------------------------
            Total |      1,000      100.00

. revrs drink

. tab revdrink

         revdrink |      Freq.     Percent        Cum.
-------------------+-----------------------------------
            Never |        300       30.00       30.00
A few times a Year |        301       30.10       60.10
     Once A month |        159       15.90       76.00
      Once a Week |         40        4.00       80.00
 Almost_Every_Day |        101       10.10       90.10
        Every_Day |         99        9.90      100.00
-------------------+-----------------------------------
            Total |      1,000      100.00


-revrs- accepts a variable list, and without any options will create a 
new variable with �rev� appended to the front of the original 
variable(s) name. The �REPLace- option automatically overwrites the 
original variable (keeping its name) with the reversed version. 
Finally, it must be noted that �revrs- does not deal with the values 
themselves, only their order. So if the actual values are of 
importance, an extra step would be needed.

The program utilizes Roger Newsom�s �sencode- which will be installed 
(if not already) alongside �revrs- when done from inside Stata.

Hopefully it will be as helpful in saving time and headaches for others 
as it has for me, and suggestions and comments are, as usual, more than 
welcomed.

Thanks, Kyle C. Longest
Dept. of Sociology
University of North Carolina � Chapel Hill
klongest@email.unc.edu




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