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Confidence Interval for a Proportion Exploration

The applet below allows you to explore a single confidence interval for a proportion (a 1-proportion z-interval). Set the population proportion, sample size, and confidence level using the sliders. There is 1 confidence interval at your chosen confidence level, based on 1 random sample of your chosen sample size, from a population with your chosen proportion. Once you set your sliders, click on the NEW RANDOM SAMPLE button to create a new confidence interval based on a new sample for your chosen settings. On average, the percentage of confidence intervals that contain the population proportion will be equal to the chosen confidence level. You will notice that larger sample sizes produce shorter confidence intervals (why?). You will notice that larger confidence levels produce longer confidence intervals (why?)