I'm working on a paper right now and I'm struggling with this. I have a statistic I know at the national level but I can't find any data of it at the state level, which is what I need it for.

If I remember correctly, there's a method for using data that comes witha large group for a much smaller group and then calculating a margin of error for that small group, but I can't for the life of me remember what the method is. If you could do something as simple as telling me what to google that would be a big help.