Differences between the skills and location of unemployed workers and available job vacancies. These help to explain why unemployment exists at the same time as unsatisfied demand for labour. Mis-match may occur because the location and skill patterns of new entrants to the labour market, those finishing education and immigrants, do not match the pattern of those leaving the labour market through retirement or emigration. It is increased by rapid changes in the pattern of demand for labour through changes in tastes or technology. Methods by which mis-match can be reduced include retraining, regulation of migration, industrial relocation, and changes in the relative wages of different occupations.