I think this might be a problem if you have a poll where a lot of people answer to one question, but only a few answer to another question, because it only applies to part of the people. Like say one question 200 people reply to one question, because it applies to everyone, and then in the next question only seven people answer in total, because it doesn't concern the other 193 people, then in the second question all would be squished to the utmost left.