Confidence Interval for Proportion

Statistics · Axiom Academy

EXAMPLE Confidence Interval for Proportion Constructing a 95% confidence interval for a population proportion with condition checking Excellent work! You've completed this confidence interval example. Here's what we learned: Always check conditions first: Before constructing a confidence interval for a proportion, verify that the sample is random and that both np and n(1-p) are at least 10. Standard error formula: The standard error for a proportion is SE = sqrt(p(1-p)/n) , which measures the variability of the sample proportion. Margin of error interpretation: The margin of error is the radius of the confidence interval, calculated as the critical value times the standard error. Confidence interval interpretation: We are 95% confident that the true population proportion lies between 0.646 and 0.734, meaning if we repeated this process many times, about 95% of intervals would contain the true proportion. Practice constructing confidence intervals with different confidence levels (90%, 99%) and sample sizes to build your intuition!

This is the written version of the interactive lesson above. See the full Statistics course.