See: http://n4.nabble.com/panel-data-td1749549.html
On Thu, Apr 8, 2010 at 12:55 PM, Richard Saba <saba...@auburn.edu> wrote: > I have a data set with observations on 549 cities spanning an 18 year > period. However, some of cities did not report in one or more of the 18 > years. I would like to implement the procedure suggested by Wooldridge > section 17.1.3 in his "Econometric analysis of cross section and panel data" > to correct for attrition. For example the table below indicates that the 3rd > and the 7th cities in the data set do not have observations for several > years. The Wooldridge procedure requires the generation of a selection > variable that takes on the value of 1 if the city reports in that year and 0 > otherwise. How do I assign a zero to a city when it does not have an > observation for that year? > > For example. Suppose I have the following data set. The observation range > over three years 1990-1992. But some cities did not report in some years. > > > The original data looks like this: > > Cicoid year other_variables seclection-variable > > 1 1990 x x x x x x x 1 > 1 1991 xxxxxxxxxx 1 > 2 1991 xxxxxxxxxx 1 > 3 1990 xxxxxxxxxx 1 > 3 1991 xxxxxxxxxx 1 > 3 1992 xxxxxxxxxx 1 > > I would like to get a data set that looks like this: > > Cicoid year other_variables seclection-variable > > 1 1990 x x x x x x x 1 > 1 1991 xxxxxxxxxx 1 > 1 1992 ....... 0 > 2 1990 ........ 0 > 2 1991 xxxxxxxxxx 1 > 2 1992 ........ 0 > 3 1990 xxxxxxxxxx 1 > 3 1991 xxxxxxxxxx 1 > 3 1992 xxxxxxxxxx 1 > > > I can reshape the data using STATA with the following three simple commands: > xtset Cicoid year > tsfill ,full > replace selection_variable=0 if selection_variable==. > > I proclaim the data as a panel series identifying the ID and TIME index > variables. Then use the time-series fill command. > > I have searched the help and vignettes of both the "zoo" and "plm" packages > but cannot find the solution. > Can anyone help? Thanks, > > Richard Saba > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
