Which version of the Eysenck Personality Profiler is best? 6-, 12- or 20-items per scale

Data provided by 400 first year undergraduate students were analysed to develop two short forms of the Eysenck Personality Profiler (EPP) in which each of the 22 primary scales is assessed by a 6-item and a 12-item version instead of the usual 20-item per scale measure. In comparison with the 6-item per scale measure, the 12-item version retains more of the characteristics of the long version and seems a good compromise between quality of data and administration time.