Exercise

# CI via approximation

The approximation shortcut offers an alternative method of describing the sampling distribution. In this exercise, you will apply the approximation shortcut to build a confidence interval for the proportion of respondents that live in the pacific region.

When building *any* confidence interval, note that you use three ingredients: the point estimate (here, `p_hat`

), the SE, and the number of standard errors to add and subtract. For a sampling distribution that is bell-shaped, adding and subtracting two SEs corresponds to a confidence level of 95%. When you use the bootstrap, you can check that the distribution is bell-shaped because you have a have the bootstrap distribution to plot. When you use the approximation, you're flying blind – well, not quite blind, but you *are* dependent on the "rule of thumb" to ensure that you're working with a bell shape.

Instructions 1/2

**undefined XP**

- Calculate the sample size,
`n`

(which is the number of rows). - Calculated the observed statistic,
`p_hat`

, as the proportion of people in the "pacific" meta-region.