Part 1: More practice constructing and interpreting confidence intervals As a review of material from Week 10, remember the general form of a confidence interval: ?a???? ??a?i??ic :l: ?a??i? '2? ????? The sample statistic is always right in the center of the interval since it is used to construct the interval, and the margin of error determines the width of the interval. Once we construct a confidence interval, we end up with a lower bound for the interval and an upper bound for the interval, and we can use that information to write a statement about how confident we are the interval includes the true population parameter. When we have data in the form of proportions, the formula we use to construct our confidence interval is given below. fl Fitz.( now) Recall that '? is a sample statistic; it is the sample proportion. Our sample size is n, and 2* is a standardized value (see below) that corresponds to the level of confidence we have chosen