How does sample size impact the interval?
Increasing the sample size reduces the standard error, which in turn narrows the confidence interval. A larger sample provides a more precise estimate of the population parameter.
What does "95% confidence" actually mean?
It means that if you were to take 100 different samples and compute a confidence interval for each, approximately 95 of those intervals would contain the true population mean. It describes the reliability of the estimation process.
What is the difference between Z-tests and T-tests?
A Z-test is used when the population standard deviation is known and the sample size is large (typically n > 30). A T-test is used when the population standard deviation is unknown and the sample standard deviation is used as an estimate instead.