Why are MIZs not included in my CMA ranking areas report from ENVISION?

Each of the Metropolitan Influenced Zone (MIZ) geographies (strong, moderate, weak and no) are national level polygons and are not created at lower levels of geography. We do not include MIZs in the Ranking Areas report using a sub-national trade area because their counts would be representative of the national count for each of the MIZs and not of the selected trade area.