The study looked at how well the economies in West Africa sync up in terms of their ups and downs. They used a method called the Hodrick-Prescott filter to break down the GDP growth rates of these countries into two parts - one that stays the same over time and one that changes. They found that while some sub-economies in West Africa have similar business cycles, overall, the countries in the region have different cycles. This suggests that creating a bigger monetary union in 2020 with all West African countries might not be a good idea. However, there is a chance that forming this union could help fix economic differences in the region after it's already been done, rather than before.