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Re: st: Graphing longitudinal profiles


From   Maarten Buis <maartenlbuis@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Graphing longitudinal profiles
Date   Thu, 1 Dec 2011 17:40:34 +0100

On Thu, Dec 1, 2011 at 5:26 PM, Thomas Speidel <thomas@tmbx.com> wrote:
> I am having difficulties creating a connected line graph for a longitudinal
> dataset.  <snip>
> Notice the vertical line going from 13 to 19 on the y-axis. Why?

The problem are the missing values. The conect(L) starts a new line if
t[_n+1] < t[_n]. So for id 88 to id 93 there will be a line going from
19 to 14 at t=0, which is not what you want. One solution is in the
example below:

*------------ begin example ------------
drop _all
input id   time   value
   84      0      15
   84      1      18
   84      2      17
   88      0      19
   88      1       .
   88      2       .
   93      0      14
   93      1      19
   93      2      19
   94      0      16
   94      1      20
   94      2      20
   97      0      13
   97      1       .
   97      2       .
   98      0      17
   98      1      19
   98      2      20
   99      0      17
   99      1      18
   99      2      20
end
sort id time
gen byte notmiss = !missing(value)
bys id : egen Nnotmist = total(notmiss)
twoway line value time if Nnotmist >=2 , connect(L)
*---------------- end example -----------------

Hope this helps,
Maarten



--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany


http://www.maartenbuis.nl
--------------------------
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