0
โ
Lower bound
โ
Upper bound
โ
Margin of error
โ
Standard error
The confidence interval is mean ยฑ zยท(ฯ/โn). It gives a range that is likely to contain the true population mean at the chosen confidence level.
Frequently Asked Questions
What does a 95% confidence interval mean?
If you repeated the sampling many times, about 95% of the intervals built this way would contain the true population mean. It is not a 95% probability that the mean is in this single interval.
Calculate a confidence interval for a mean from the sample mean, standard deviation and size.