The level of education is captured by two dummy variables, the first one being equal to unity for all individuals who have at least finished upper-secondary education, and hence also takes value one for those who have a tertiary degree. The second one being equal to unity for all individual who have finished tertiary education. Hence, the coefficient on the first dummy gives the impact of an upper-secondary or post-secondary non-tertiary education relative lower-secondary education or less and the coefficient on the second dummy gives the impact of tertiary education relative to upper-secondary or post-secondary non-tertiary education. Since this technique is still fairly new, the more established approach by Koenker and Bassett (1978) is also used by Fournier and Koske (2012).