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From |
"Lima, Julie" <julie_lima@brown.edu> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: on data transformation |

Date |
Wed, 20 Jul 2011 14:56:10 -0500 |

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 * * 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/

**Follow-Ups**:**Re: st: on data transformation***From:*"Lima, Julie" <julie_lima@brown.edu>

**References**:**st: on data transformation***From:*rado645-bg@yahoo.de

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