search for: patientinformation1

Hi, I have imported one dataset in R. I want to calculate the percentage of missing values for each month (May 2006 to March 2007) for each variable. Just to begin with I tried the following code : *for(i in 1:length(dos)) for(j in 1:length(patientinformation1) if(dos[i]=="May-06" && patientinformation1[j]=="") a <- j+1 a* The above code was written to calculate the number of missing values for May 2006, but I am not getting the correct results. Can anybody help me? Thanks, Shreyasee [[alternative HTML version deleted]]