R-GUI How do i aggregate survey data collected for multiple years and see if they contain a variable?
If I understand your question correctly you'd like to obtain the proportion of missing values of a specific column in your dataset.
This can be obtained with the plyr library

For example:

library(plyr)
df &lt;- data.frame(Study=c('Study_1', 'Study_1', 'Study_2', 'Study_3'), col1=c(NA,NA,5,8), col2=c(8, NA, NA, 7))

column &lt;- 'col1'           # is the column your are interested in

ddply(df, .(Study), function(x){
  length(which(is.na(x[column])))/nrow(x)*100
})

Study  V1
Study_1 100
Study_2   0
Study_3   0


Study_1 has 100% missing values and the other studies none, so except Study_1 all studies contains some information