https://www.khanacademy.org/math/statistics-probability/confidence-intervals-one-sample/estimating-population-proportion/v/confidence-interval-example 2021-02-11T09:29:38Z Confidence interval example Sal calculates a 99% confidence interval for the proportion of teachers who felt computers are an essential tool. Sal Khan video https://cdn.kastatic.org/googleusercontent/OQos86xxbWHCv5N5u6huTvLaUIDPj5Pzxel-A38aBMESFkdCuWMWWyTu-hnspsmo7G3qATcX4QGeUlGOQym5opNJnw Confidence interval example Sal calculates a 99% confidence interval for the proportion of teachers who felt computers are an essential tool. https://cdn.kastatic.org/ka-youtube-converted/SeQeYVJZ2gE.mp4/SeQeYVJZ2gE.mp4 1116 One-proportion z-intervals https://www.khanacademy.org/math/ap-statistics/xfb5d8e68:inference-categorical-proportions/one-sample-z-interval-proportion/v/conditions-for-valid-confidence-intervals 2022-10-07T00:58:19.561984208Z Conditions for valid confidence intervals for a proportion There are three conditions we need to satisfy before we make a one-sample z-interval to estimate a population proportion. We need to satisfy the random, normal, and independence conditions for these confidence intervals to be valid. video https://cdn.kastatic.org/googleusercontent/WXkaWS_krA9fj1feeNgo3iYpdIB0-awJsjbT4q9_JuCTBtUAeU1ck48PviSmy646GXvyFtu8ih26TRpJzXYuzY5sog Conditions for valid confidence intervals for a proportion There are three conditions we need to satisfy before we make a one-sample z-interval to estimate a population proportion. We need to satisfy the random, normal, and independence conditions for these confidence intervals to be valid. https://cdn.kastatic.org/ka-youtube-converted/8E8YQY5qE3s.mp4/8E8YQY5qE3s.mp4 404 One-proportion z-intervals https://www.khanacademy.org/math/ap-statistics/xfb5d8e68:inference-categorical-proportions/one-sample-z-interval-proportion/v/conditions-for-confidence-intervals-worked-examples 2022-10-07T00:58:19.561984208Z Conditions for confidence interval for a proportion worked examples Conditions for confidence intervals for a population proportion worked examples--random condition, independence condition and normal condition. video https://cdn.kastatic.org/googleusercontent/m-UvsZ1jTGJVSli8D-rwP4zvGO-9nsve2Z6i-46dgC-vYWmkF2tXKVD9OvCsXwdvnqeuopY9Woa_mK6DbjnoHwA Conditions for confidence interval for a proportion worked examples Conditions for confidence intervals for a population proportion worked examples--random condition, independence condition and normal condition. https://cdn.kastatic.org/ka-youtube-converted/PwMqupyG4D0.mp4/PwMqupyG4D0.mp4 294 One-proportion z-intervals https://www.khanacademy.org/math/ap-statistics/xfb5d8e68:inference-categorical-proportions/one-sample-z-interval-proportion/a/conditions-inference-one-proportion 2021-07-01T02:19:27Z Reference: Conditions for inference on a proportion article https://www.khanacademy.org/math/ap-statistics/xfb5d8e68:inference-categorical-proportions/one-sample-z-interval-proportion/e/conditions-one-sample-z-interval-proportion 2026-06-23T13:38:27.041531116Z Conditions for a z interval for a proportion Practice determining if the conditions for a one-sample z interval for a proportion have been met or not. Jeff Dodds exercise https://www.khanacademy.org/math/ap-statistics/xfb5d8e68:inference-categorical-proportions/one-sample-z-interval-proportion/v/critical-value-for-a-given-confidence-level 2022-11-16T04:22:43.7414897Z Critical value (z*) for a given confidence level If we want to be 95% confident, we need to build a confidence interval that extends about 2 standard errors above and below our estimate. More precisely, it's actually 1.96 standard errors. This is called a critical value (z*). We can calculate a critical value z* for any given confidence level using normal distribution calculations. video https://cdn.kastatic.org/googleusercontent/r7bks7duv8lrpueEwwhj7LT4moYkop1hzSbNpmqwI5kgWGeOx30v3HcxMfCNkhwVmpvZxvu0G-xqfd3Od4WjwzNFGQ Critical value (z*) for a given confidence level If we want to be 95% confident, we need to build a confidence interval that extends about 2 standard errors above and below our estimate. More precisely, it's actually 1.96 standard errors. This is called a critical value (z*). We can calculate a critical value z* for any given confidence level using normal distribution calculations. https://cdn.kastatic.org/ka-youtube-converted/VILsYH84HJE.mp4/VILsYH84HJE.mp4 382 One-proportion z-intervals https://www.khanacademy.org/math/ap-statistics/xfb5d8e68:inference-categorical-proportions/one-sample-z-interval-proportion/e/finding-critical-value-z-for-confidence-level 2021-07-01T02:19:29Z Finding the critical value z* for a desired confidence level Practice finding the critical value z* for some given confidence level. Jeff Dodds exercise https://www.khanacademy.org/math/ap-statistics/xfb5d8e68:inference-categorical-proportions/one-sample-z-interval-proportion/v/example-calculating-confidence-interval 2022-10-07T00:58:19.561984208Z Example constructing and interpreting a confidence interval for p Check conditions, calculate, and interpret a confidence interval to estimate a population proportion video https://cdn.kastatic.org/googleusercontent/vfGN_MOwvuVtG3A8_9o8lQdXqYwkn-m38EP4DmgHqC0PBTtJ8qgQP7u62MCuMdzzvWQtTJjx1woN0bJqtr7nnMY Example constructing and interpreting a confidence interval for p Check conditions, calculate, and interpret a confidence interval to estimate a population proportion https://cdn.kastatic.org/ka-youtube-converted/sjG9Ns_8x6c.mp4/sjG9Ns_8x6c.mp4 395 One-proportion z-intervals https://www.khanacademy.org/math/ap-statistics/xfb5d8e68:inference-categorical-proportions/one-sample-z-interval-proportion/e/calculating-one-sample-z-interval-proportion 2026-06-23T13:38:27.041531116Z Calculating a z interval for a proportion Practice constructing a one-sample z interval for a proportion. Jeff Dodds exercise https://www.khanacademy.org/math/ap-statistics/xfb5d8e68:inference-categorical-proportions/one-sample-z-interval-proportion/a/interpreting-z-interval-proportion 2021-07-01T02:19:29Z Interpreting a z interval for a proportion article https://www.khanacademy.org/math/ap-statistics/xfb5d8e68:inference-categorical-proportions/one-sample-z-interval-proportion/v/determining-sample-size-based-on-confidence-and-margin-of-error 2022-10-07T00:58:19.561984208Z Determining sample size based on confidence and margin of error Determining sample size based on confidence level and margin of error video https://cdn.kastatic.org/googleusercontent/gv6WYsLSFop4QPRZBRNWJOwXdoBE8a2XqbfXVUAvmFgmDM5pY52m1WdoBYQTDPocTRh3_OtdtH3PnG0XHEtD1yk Determining sample size based on confidence and margin of error Determining sample size based on confidence level and margin of error https://cdn.kastatic.org/ka-youtube-converted/VyFs7fsWE6w.mp4/VyFs7fsWE6w.mp4 481 One-proportion z-intervals https://www.khanacademy.org/math/ap-statistics/xfb5d8e68:inference-categorical-proportions/one-sample-z-interval-proportion/e/sample-size-margin-error-one-sample-z-interval 2026-06-23T13:38:27.041531116Z Sample size and margin of error in a z interval for p Practice estimating what sample size is required for a given margin of error in a one-sample z interval for a proportion. Jeff Dodds exercise