2. Part 1: The Interval of Numbers

Part 1: The Interval of Numbers

In order to create an interval of “cushion” about our point estimate , we will use the following formula: ± margin of error.

The “plus-or-minus” means that we want to account for the fact that our point estimate  could be either below or above the true (unknown) population proportion p.

The margin of error depends on three factors:

  1. The level of confidence C
  2. The sample size n
  3. The standard deviation of the distribution of the sample proportion: