Confidence Interval for a Population Proportion

To obtain the confidence interval for a proportion, you need:

• Point estimate of a proportion, [latex]\hat{p}[/latex]
• Margin of error, [latex]ME = z^{*} \cdot (\text{standard error})[/latex]
  • standard error = [latex]\sqrt{\frac{\hat{p}(1-\hat{p})}{n}}[/latex]
  • [latex]z^{*}[/latex] is the point on the standard normal distribution such that the proportion of area under the curve between [latex]−z^{*}[/latex] and [latex]+z^{*}[/latex] is [latex]C[/latex], the confidence level.