Vocational qualifications make a marked difference to employees’ earnings, but the effect varies widely between sectors and occupations, research has indicated.Workers gaining a level 3 apprenticeship earn an average of 22 per cent more than those with no such qualifications, according to research conducted by the University of Sheffield and published by the UK Commission for Employment and Skills. City & Guilds, RSA, BTEC and other vocational qualifications all boosted earnings to a greater or lesser extent, by a differential of between 5 and 23 per cent.