After 2003, the eph was carried our four times a year, with respondent households being surveyed twice in two consecutive semesters in year 1 and twice in the same semesters in year 2 and again in year 3 before being rotated out of the sample. This shift should make it possible to do panel data analyses of post-2003 labour market data. Fourth, we put both individuals (mother and synthetic non-mother) in a new sample of matched individuals.