Table C 1 shows the results of the OLS estimation obtained with the pooled cross-section data series for 29 OECD countries (with an average of 10 observations per country over the 25 years period). Demographic variables are included sequentially and the results from the different steps are reported in the different columns to best identify how the different explanatory factors are linked to each other. The proportion of jobless families and maternal the employment rates are two highly correlated variables, and for this reason they were introduced simultaneously in the model specifications (except in column 8 for a final robustness check).