Statalist


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

st: merge by nearest date


From   Joseph Wagner <joseph.wagner@wright.edu>
To   statalist@hsphsun2.harvard.edu
Subject   st: merge by nearest date
Date   Tue, 08 Sep 2009 12:15:33 -0400

I am using Stata ver 8.2 and wish to merge two files each with an idcode
and a date.  (I know that more recent versions of Stata can handle this
more capably but funds are short at this time so I make do with what I
have.)  None of the dates in using matches exactly with master.  I get
the following:

. tab _merge

     _merge |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        585        1.82        1.82
          2 |     31,554       98.18      100.00
------------+-----------------------------------
      Total |     32,139      100.00

This is what I expected but I would like to see how close I can get a
pair (master and using) that are within one week of one another.  If I
calculate a simple difference between master and the next using above
will miss any closer using if it is below the master.  I hope this makes
sense.  Here is a snippet of the data:


idcode      visit    _merge
FEL00057    26 Sep 33    2
FEL00057    30 Sep 33    1
FEL00057    22 Nov 33    2
FEL00057    24 Jan 34    2
FEL00057    28 May 34    2
FEL00057    03 Aug 34    2
FEL00057    23 Sep 34    1
FEL00057    24 Sep 34    2
FEL00057    27 Nov 34    2
FEL00057    28 Jan 35    2
FEL00057    27 Mar 35    1
FEL00057    30 Mar 35    2

If my data is arranged in this fashion, how do I best get the closest
pair of using and master?

*
*   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/



© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index