Statistics on the Wage of Persons with Disabilities Sampling errors: variation coefficients for the annual earnings per worker variable Type of contract Unidades: coefficient of variation ,Total,Persons without disabilities,Persons with disabilities, Total,0,42,0,43,2,51, Permanent contract,0,51,0,52,2,74, Temporary contract,1,2,1,22,5,27, Notas: Persons with disabilities refers to persons formally recognised as disabled, with a degree of dissability of 33% or over, according to the procedure for evaluating this established in the RD 1971/1999 and modified by the RD 1856/2009. 2) When the box is marked with a '-' sign before the data, it indicates that the number of sample observations is between 100 and 500, so the figure is subject to great variability. Fuente: Spanish National Statistics Institute