the number of workers across skillgroups and within a sector is identified under the assumption that within sectors workers engage in the same amount of hours across the different labour categories highskilled mediumskilled and lowskilled in the second step to calculate a wage for each of these worker categories the value added of a given worker category the wage bill is divided by the number of workers in that category and sector the resulting output is an average wage rate for each of the three categories of workers within a sector giving rise to a maximum of countrysectorskill categoryyear wage observations this information is then used to calculate aggregate measures of wage inequality a gini coefficient using weights capturing the number of workers across skill categories and sectors within a country box great care has been taken to harmonise crosscountry measures of inequality by the oecd in the income distribution database which does not suffer from the problem of using income and expenditures in different years