The adjusted pay gap is the difference in gross pay between two different groups with comparable characteristics. In order for the groups to have comparable characteristics for the calculation, the part of the earnings difference that is based on structural differences is eliminated. Structural differences include, for example, the level of education, qualifications, work experience and scope of employment.

The unadjusted pay gap is the difference between the average gross hourly wage of two different groups. These groups could be, for...