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Re: st: on data transformation


From   "Lima, Julie" <julie_lima@brown.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: on data transformation
Date   Wed, 20 Jul 2011 14:57:23 -0500

Looks like Nick beat me to it!  :)

On Wed, Jul 20, 2011 at 2:56 PM, Lima, Julie <julie_lima@brown.edu> wrote:
> I'm not sure if I'm reading your data correctly, but there are a few
> ways you could do it.  I would try the following:
>
> sort by x and year, create a variable that indicated the maximum value
> for event in a given year per x, and then keep only those observations
> where this new variable==1.  So,...
>
> sort x year
> by x year: egen evtyr=max(event)
> keep if evtyr==1
>
> Assuming, event is 1 or missing (and there are no other values), The
> first 2 lines should result in the following:
>
>> x  week      var1  var2 year event  evtyr
>>
>> x1 2006w2 var1 var2 2006
>> x1 2006w3 var1 var2 2006
>> x1 2006w4 var1 var2 2006
>> x1 2007w7 var1 var2 2007            1
>> x1 2007w8 var1 var2 2007            1
>> x1 2007w9 var1 var2 2007            1
>> x1 2007w10 var1 var2 2007 1        1
>>
>> x2 2008w2 var1 var2 2008
>> x2 2008w3 var1 var2 2008
>> x2 2008w4 var1 var2 2008
>> x2 2009w9 var1 var2 2009            1
>> x2 2009w8 var1 var2 2009            1
>> x2 2009w9 var1 var2 2009            1
>> x2 2009w10 var1 var2 2009 1        1
>
> then the last line would keep all obervations within the year of
> interest (evtyr=1) for each x .
>
> Goodluck, Julie
>
>
> On Wed, Jul 20, 2011 at 2:41 PM,  <rado645-bg@yahoo.de> wrote:
>> Dear all,
>>
>> I would like to ask for help with data transformation. I have data on objects
>> x1, x2,x3  that are observed over time (weeks). I have variables var1 and var2
>> for each objects and also variable indicating the year of observation. In
>> addition, a variable "event" indicates the time period when an event has
>> occurred.
>>
>>
>> The columns of the panel data set look as follows:
>>
>> x  week      var1  var2 year event
>>
>> x1 2006w2 var1 var2 2006
>> x1 2006w3 var1 var2 2006
>> x1 2006w4 var1 var2 2006
>> x1 2007w7 var1 var2 2007
>> x1 2007w8 var1 var2 2007
>> x1 2007w9 var1 var2 2007
>> x1 2007w10 var1 var2 2007 1
>>
>> x2 2008w2 var1 var2 2008
>> x2 2008w3 var1 var2 2008
>> x2 2008w4 var1 var2 2008
>> x2 2009w9 var1 var2 2009
>> x2 2009w8 var1 var2 2009
>> x2 2009w9 var1 var2 2009
>> x2 2009w10 var1 var2 2009 1
>>
>> I have many variables x that differ in number of weeks and years. I need however
>> to keep the year when the event has happened and dropped any previous years.
>> Given my data set, is this possible to be done in Stata?
>>
>>
>> Many thanks in advance.
>>
>> KR,
>> Rado
>>
>>
>> *
>> *   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/
>>
>
>
>
> --
> *************************************
> Julie Lima, MPH, PhD
> Senior Research Analyst
> Brown University
> Center for Gerontology and Health Care Research
> Providence, RI
>
> Mailing Address
> 1316 Old Oak Trail
> Flower Mound, TX 75028
> p: 972-355-7814
>



-- 
*************************************
Julie Lima, MPH, PhD
Senior Research Analyst
Brown University
Center for Gerontology and Health Care Research
Providence, RI

Mailing Address
1316 Old Oak Trail
Flower Mound, TX 75028
p: 972-355-7814

*
*   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/


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