• CIs are formed for the unknown population parameter (such as the population proportion $$p$$), based on a sample statistic (such as the sample proportion $$\hat{p}$$).
• Most CIs have the form $\text{Statistic} \pm \overbrace{(\text{Multiplier} \times \text{standard error})}^{\text{Called the `margin of error'}}.$
• The margin of error is $$(\text{Multiplier} \times \text{standard error})$$.