For example, the study of the Ministry of Employment and Professional Insertion of Youth and the World Bank (2009) based on longitudinal data (tracer study from the 2004 cohort) show's the existence of imbalances between supply and demand for skills at the post-secondary level. Some qualifications and fields of studies are characterised by long duration unemployment and withdrawal from activities. They find that unemployment rates are particularly high among BTS graduates of agriculture, commerce and administration (Ministry of Employment and Professional Insertion of Youth and the World Bank, 2009).