3. Confidence Level
What it is: The confidence level is the percentage of times you expect to capture the true population parameter (e.g., mean, proportion) if you repeated your study many times. It’s related to the concept of a confidence interval.
Common value: The most common confidence level is 95%, but others like 90% or 99% are also used.
How it’s used: A 95% confidence level means that if you repeated your study 100 times, you’d expect the true population parameter to fall within your confidence interval in 95 of those studies.
Example: If you calculate a 95% confidence interval for the average height of students to be [160 cm, 170 cm], it means you’re 95% confident that the true average height lies between 160 cm and 170 cm.