Oftentimes on national issues like elections, you see news media reports polls after polls and each time they point out the results are within the margin of error of 3%. You may have been wondering where does the 3% come from. As you learn about control charts for attributes try to figure out the answer to this question. Note that in those polls the pollster normally asks 1000 people at random and then reports the proportion voting for a candidate or a particular proposition.