Hi, I have a dataset (728 obs) containing three variables code of a company,
year and revenue. Some companies have a complete history of 5 years, others
have not a complete history (for instance observations for three or four
years).I would like to determine the companies with a complete history using a
dummy variables.I have written the following program but there is somehting
wrong because the dummy variable that I have create is always equal to zero.Can
somebody help me?Thanks, gm
z<-read.table(file="c:/Rp/cddat.txt", sep="", header=T)
attach(z)
n<-length(z$cod) // number of obs dataset
d1<-numeric(n) // dummy variable
for (i in 5:n) {
if (z$cod[i]==z$cod[i-4]) // cod is the code of a company
{ d1[i]<=1} else { d1[i]<=0} // d1=1 for a company with complete
history, d1=0 if the history is not complete }d1
When I run the program d1 is always equal to zero. Why?
Once I have create the dummy variable with subset I obtains the code of the
companies with a complete history and finally with a merge I determine a panel
of companies with a complete history.But how to determine correctly d1?My best
regards, gm
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