qualification mismatch is determined based on a comparison of a worker s qualification level expressed as the international standard classification of education isced level corresponding to his or her highest educational qualification and what is thought to be the required qualification level for his or her occupation code the international standard classification of occupations isco code attached to the job he or she holds because isced levels do not accurately reflect skills not even those acquired in initial education and isco codes do not accurately describe jobs the resulting measure does not precisely describe how a worker s skills set matches the skills needed to carry out his or her tasks at work skills mismatch however refers more precisely to a worker s actual skills and to the skills needed in his or her specific job