Zero returns to compulsory schooling: Is it certification or skills that matters?

The policy goal was to increase the number of high school graduates. The analysis shows that the change led to a decrease in the high school dropout rate of approximately 20%. However, there were no benefits in terms of employment or higher wages. I investigate several explanations for this finding and present suggestive evidence in support of the skill-based explanation that no more labor-market relevant skills were learned during this extra year of school compared to those skills previously learned out of school.