Eventually, regardless of the collaboration scale, the most challenging issue in global collaboration is responsibility - sharing and commitment. (science.sciencemag.org)
Further, the certification program also addresses challenging issues of professional breeding, including breeding ages, litter limits, and transparency. (caninecarecertified.org)
One of the most challenging issues in assessing teacher compensation is determining how much time teachers spend working compared to other professionals. (papers.ssrn.com)