help ccmatch                                                     (version 1.1) 
By Daniel E. Cook {Danielecook@gmail.com}                   www.Danielecook.com
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ccmatch

     ccmatch -- Used to randomly match cases and controls
                based on specified criteria. For instance,
                if you wanted to randomly match cases and
                controls based on age, you can use ccmatch
                to specify age as a criterion on which to
                match cases and controls and it will match
                randomly by age. You can use multiple
                variables to match based on multiple
                criteria

     ccmatch creates two variables:

                match_id gives the id of the partner an
                individual has been matched to.

                matched_pair Numbers pairs starting from
                one. Pairs will share the same number in
                this column (see example below).




Syntax

     ccmatch variable_list, cc() id()

          variable_list -- Specify variables you want each pair to share here.

          cc(var) -- Specify the variable you use to identify cases and
          controls. Must be coded 0=controls, 1=cases.

          id(var) -- Specify the variable you to name individuals/observations
          in your dataset.



Example


         match_id       matched_pair   name                     case_control   
>           age
         a6             1              a2                       0              
>           15
         a2             1              a6                       1              
>           15
         a7             2              a4                       0              
>           16
         a4             2              a7                       1              
>           16
         a8             3              a5                       0              
>           17
         a5             3              a8                       1              
>           17
         a10            4              a1                       0              
>           19
         a1             4              a10                      1              
>           19
                        .              a3                       0              
>           15
                        .              a9                       1              
>           18

     The above output is an example of what match can do. The original data
     (name, case_control, age) is unchanged, except that it has been reordered
     The command used was:

     ccmatch age, id(name) cc(case_control)

     Age was specified following ccmatch to indicate that we wanted to match
     cases/control who are the same age.

     The case/control variable is specified as an option using cc(), and the id
     of each individual is specified using id().


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note I use individual in this document but it could be interchanged with the
word 'observation' and meaning would be the same. This program should be used
in cases where each row of your dataset constitutes a single individual.
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Last Revised  12/18/12
 Update - 12/18/12
          - Huge performance improvement - works on extremely large datasets no
> w. 

 Update - 06/27/12
          - Fixed issue where a maximum of only 1600 individuals could be match
> ed. 

 Initial Release - 12/18/11