Research Project Sample Size Calculator

The confidence interval is the plus-or-minus figure usually reported in newspaper or television opinion poll results. For example, if you use a confidence interval of 4.9 and 50% percent of your sample picks an answer you can be “sure” that if you had asked the question of the entire relevant population between 45.1% (50 - 4.9) and 54.9% (50 + 4.9) would have picked that answer.