For our study, we need to find counterparts for the treatment and control groups in 2000 among students in lower secondary schools in 2003 or 2006. This can be achieved with matching methods where counterfactual 1= 1 scores are constructed using scores of students with similar characteristics to those observed in t=0. Usually, matching methods are used to make control and treatment groups more comparable, assuming that we have the same observations in each group in 1=0 and t=\ In our case, we do not want to adjust for dissimilarities among treatment and control groups. We know that students who were in vocational schools differed from those in general schools, but we are interested in whether moving students from different tracks, who differ by assumption, into the one-type comprehensive lower secondary schools, affected them similarly.