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st: RE: difficult merging issue


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: difficult merging issue
Date   Sun, 13 Jul 2008 16:48:45 +0100

I do not understand this to be a merging issue. You appear to have just
one dataset. 
In Stata, -merge- requires two datasets. 

Nor do I see why you think you need a dummy for every official. 

My guess is that you have a problem for which -collapse- is the
solution. 

However, you need to -reshape- first. 

Here is a guess at an analogue to your problem. 

. l

     +--------------------------------------+
     | Meet   WhoL   ScoreL   WhoW   ScoreW |
     |--------------------------------------|
  1. |    1      B        3      A       12 |
  2. |    2      A        6      B        7 |
  3. |    3      D        3      C        4 |
  4. |    4      C        4      D        3 |
     +--------------------------------------+

. reshape long Who Score, i(Meet) string
(note: j = L W)

Data                               wide   ->   long
------------------------------------------------------------------------
-----
Number of obs.                        4   ->       8
Number of variables                   5   ->       4
j variable (2 values)                     ->   _j
xij variables:
                              WhoL WhoW   ->   Who
                          ScoreL ScoreW   ->   Score
------------------------------------------------------------------------
-----

. l

     +-------------------------+
     | Meet   _j   Who   Score |
     |-------------------------|
  1. |    1    L     B       3 |
  2. |    1    W     A      12 |
  3. |    2    L     A       6 |
  4. |    2    W     B       7 |
  5. |    3    L     D       3 |
     |-------------------------|
  6. |    3    W     C       4 |
  7. |    4    L     C       4 |
  8. |    4    W     D       3 |
     +-------------------------+

After that, you can -collapse- by -Who-. 

Nick
n.j.cox@durham.ac.uk 

Rufus Peabody

I'm doing an analysis of college football officiating and have a large  
dataset.  Each game played is an observation.  There are 7 types of  
officials, and I have an ID for each official.  I have the 7 official  
variables, but the problem is that officials are not confined  
exclusively to one type---for example, one official might be "Referee"  
one game and "Line Judge" another.  What I did to alleviate this  
problem was create dummies for each official (there are 596 in total).

Now, the major issue:  I would like to somehow transform this so that  
each official is an observation and I have mean(penalties),  
mean(penalty yards), total games, etc. as variables.  This would mean  
there should be 596 total observations.  Anybody have any suggestions  
of how to tackle this problem?

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